Hi, i have a problem with @Asynchronous method

this is my Bean

package com.domain.matricehrm.session;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import javax.ejb.Remove;
import javax.ejb.Stateful;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.jboss.seam.ScopeType;
import org.jboss.seam.annotations.Destroy;
import org.jboss.seam.annotations.In;
import org.jboss.seam.annotations.Logger;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.annotations.Out;
import org.jboss.seam.annotations.Scope;
import org.jboss.seam.annotations.datamodel.DataModel;
import org.jboss.seam.annotations.web.RequestParameter;
import org.jboss.seam.log.Log;

import com.domain.matricehrm.entity.Employee;
import com.domain.matricehrm.entity.Paymenttask;
import com.domain.matricehrm.entity.Payrollperiod;

@Stateful
@Scope(ScopeType.SESSION)
@Name("paymentbillingAction")
public class PaymentbillingAction implements Paymentbilling, Serializable {

        /**
         * 
         */
        private static final long serialVersionUID = 1L;
        private Integer period;
        private String loccode;
        private String deptcode;
        private String groupcode;
        private String idemployee;
    private List<String> itemselects = new ArrayList<String>();
        
        public String[] noRegs;
    
    
        public PaymentbillingAction(){

        }

        
        
        public PaymentbillingAction(Integer period, String loccode, String deptcode, String groupcode,
                        String idemployee, List<String> itemselects){
                this.period = period;
                this.loccode = loccode;
                this.deptcode = deptcode;
                this.groupcode = groupcode;
                this.idemployee = idemployee;
                this.itemselects = itemselects;
        }

        
    @DataModel
    List<Employee> selectedemployees;

    @DataModel
    List<Payrollperiod> pperiods;
    
    @In(required = false)
    Asynpayment asyncpayment;
   
    @PersistenceContext //(type=PersistenceContextType.EXTENDED)
    EntityManager em;

    @DataModel
    List<String> employeeRegisters;
    
    @Out(required = false)
    Employee employee;
    
        @Logger
        private Log log;

    @RequestParameter
    String freqpay;
        
    private Paymenttask payments;
    @In(required = false)
    @Out(required = false, scope = ScopeType.SESSION)
    private List<Employee> hasilEmployee = new ArrayList<Employee>();
    private Paymenttask paytask = new Paymenttask();
    @In(required = false)
    @Out(required = false, scope = ScopeType.SESSION)
    private String paramRegister = new String();
    @In(required = false)
    @Out(required = false, scope = ScopeType.SESSION)
        private Integer periodID;
    
    // VARIABLE - VARIABLE
        String locationcode;
        String departmentcode;
        String employeegroup;
        String employeeid;
        String payfrekuency;
        String[] arrayRegs;
        String pemisah = ",";
        String semikolon = "'";
        Integer regsize;
    
    
    @SuppressWarnings("unchecked")
        public void pilihPegawai(){
//      inisialisasi();
                periodID = getPeriod();
                locationcode = "";
                departmentcode = "";
                employeegroup =  "";
                employeeid = "";
        List<Payrollperiod> periodes = em.createQuery("select per, taxparam from Payrollperiod per "+
                                "INNER JOIN FETCH per.taxparameter taxparam "+
                                "where per.payrollperiodid= :perID")
                                .setParameter("perID", periodID)
                                .getResultList();
        pperiods = periodes;
        for (Payrollperiod prd : pperiods)
        {
                payfrekuency = prd.getPeriodtype();
                freqpay = payfrekuency;
        }
                
                locationcode = getLoccode();
                departmentcode = getDeptcode();
                employeegroup =  getGroupcode();
                if (locationcode == null || locationcode.equals("")) { locationcode = "%"; }
                if (departmentcode == null || departmentcode.equals("")) { departmentcode = "%"; }
                if (employeegroup == null || employeegroup.equals("")) { employeegroup = "%"; }
                if (freqpay == null || freqpay.equals("")) {  freqpay = "%";}
                
                hasilEmployee = em.createQuery("select emp, pos, dep, loc, emppay, payscheme From Employee emp "+
                                "INNER JOIN FETCH emp.position pos "+
                                "INNER JOIN FETCH emp.position.department dep "+
                                "INNER JOIN FETCH emp.position.department.location loc "+
                                "INNER JOIN FETCH emp.employeepayroll emppay "+
                                "INNER JOIN FETCH emp.employeepayroll.payrollschema payscheme "+
                                "where emp.position.department.location.code like :locid "+
                                "and emp.position.department.code like :depid "+
                                "and emp.employeepayroll.payrollschema.schemaname like :scheme "+
                                "and emp.employeepayroll.payfrequency like :payfrekuen ")
                                .setParameter("locid", locationcode)
                                .setParameter("depid", departmentcode)
                                .setParameter("scheme", employeegroup)
                                .setParameter("payfrekuen", freqpay)
                                .getResultList();
                
                
    }

        
 
    
    
    public void prosesBilling(){
//      periodID = getPeriod();
                // merubah data list employee menjadi string
                employeeRegisters = new ArrayList<String>();
        employeeRegisters = getItemselects();
        if (employeeRegisters.size() > 0 )
        {
                regsize = employeeRegisters.size();
                noRegs = new String[regsize];
                noRegs = employeeRegisters.toArray(new String[regsize]);
                arrayRegs = new String[regsize];
                arrayRegs[0] = semikolon+noRegs[0]+semikolon;
                for (int n = 1; n <= employeeRegisters.size() - 1; n++)
                {
                        arrayRegs[n] = pemisah+semikolon+noRegs[n]+semikolon;
                        log.info("registerNo "+arrayRegs[n]);
                }
                
                // cara baru perubahan array ke string dengan menggunakan buffer
            StringBuffer result = new StringBuffer();
            if (noRegs.length > 0) {
                result.append(semikolon+noRegs[0]+semikolon);
                for (int i=1; i<noRegs.length; i++) {
                    result.append(pemisah);
                    result.append(semikolon);
                    result.append(noRegs[i]);
                    result.append(semikolon);
                }
            }
                paramRegister = result.toString();
                
        }else
        {
                paramRegister = semikolon+"%"+semikolon;
        }
        
        
        
        log.info("========== parsing ke synchronous proses =========>>>>>>");
        asyncpayment.prosesHitung(regs);
        System.out.println("coba ke DB");
        for(int i = 1; i<= 5; i ++)
        {
                this.paytask = new Paymenttask();
                this.paytask.setPeriodinfo("olaa ciecie beibeh");
                em.persist(this.paytask);
                log.info("simpan");
        }
    }
        
    
    public void reset() { 
    }
    
    @Destroy
    @Remove
        public void destroy() {
        
        }

    
    
    
    // getter dan setter..
    
        public void setPeriod(Integer period) {
                this.period = period;
        }

        public Integer getPeriod() {
                return period;
        }

        public void setLoccode(String loccode) {
                this.loccode = loccode;
        }

        public String getLoccode() {
                return loccode;
        }

        public void setDeptcode(String deptcode) {
                this.deptcode = deptcode;
        }

        public String getDeptcode() {
                return deptcode;
        }

        public void setGroupcode(String groupcode) {
                this.groupcode = groupcode;
        }

        public String getGroupcode() {
                return groupcode;
        }

        public void setIdemployee(String idemployee) {
                this.idemployee = idemployee;
        }

        public String getIdemployee() {
                return idemployee;
        }

        public void setItemselects(List<String> itemselects) {
                this.itemselects = itemselects;
        }

        public List<String> getItemselects() {
                return itemselects;
        }

        public void setPayments(Paymenttask payments) {
                this.payments = payments;
        }

        public Paymenttask getPayments() {
                return payments;
        }
   
}


and this is my stateless bean,

package com.domain.matricehrm.session;

import java.io.Serializable;

import javax.ejb.Stateless;

import org.jboss.seam.annotations.Logger;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.log.Log;

@Stateless
@Name("asyncpayment")
public class Asyncpayment implements Asynchronouspayment, Serializable{

        
    /**
         * 
         */
        private static final long serialVersionUID = 1L;
        /**
         * 
         */
        @Logger
    Log log;
        
    public void prosesHitung(String gila) {
         try {
          //  Contexts.getEventContext().set("payments",payments);
            do some work here..

        } catch (Exception e) {
            log.error("Error trying to process payment..", e);
        }
    }

    public void goBilling(){
        log.info("testing");
    }

        
}

this is my interface..
package com.domain.matricehrm.session;

import javax.ejb.Local;

import org.jboss.seam.annotations.async.Asynchronous;

@Local
public interface Asynchronouspayment {
        @Asynchronous
    public void prosesHitung(String gila);
        @Asynchronous
        public void goBilling();
 
}

and the problem is i can't call processHitung();
please how to solve my problem..