I am trying to run a client class to test the CustomerBean class that I wrote but its giving me an error which mentions EntityManager must be access within a transaction. I am new to EJB3 so bear with me please.
This the code for my customerBean class.

@Stateless
public class CustomerBean implements CustomerRemote {

 @Resource(mappedName = "java:/SQL")
 private DataSource SQL;

 @PersistenceContext private EntityManager em;

 public void addCustomer(TempCustomer a){
 em.persist(a); //This is where the Exception occurs ..thanks
 }

 public TempCustomer findCustomerbyID(int id) {
 return em.find(TempCustomer.class, id);
 }

 public void deleteCustomer(TempCustomer a) {
 em.remove(a);
 }

 public void deleteID(int id){
 em.remove(id);
 }

And this is my client class to test my CustomerBean class... I am just trying to add 2 customers in the table.

public class Client {
 public static void main(String[] args) throws Exception
 {
 Connection conn;
 // Step 1: Load the JDBC driver.
 Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
 System.out.println("Driver Loaded.");
 // Step 2: Establish the connection to the database.
 String url = "jdbc:sqlserver://localhost:1433;database=jdocxpt";
 conn = DriverManager.getConnection(url, "sa", "");
 System.out.println("Got Connection.");

 Context ctx = getInitialContext();
 CustomerRemote c = (CustomerRemote) ctx.lookup("CustomerBean/remote");

 TempCustomer first = new TempCustomer();
 TempCustomer second = new TempCustomer();

 System.out.println("adding Customers");
 first.setId(20);
 first.setName("aaaa");
 second.setId(21);
 second.setName("kkkk");
 c.addCustomer(first);
 c.addCustomer(second);
}

I would appreciate it if some could help me with this transaction problem.
THANKS IN ADVANCE.

the error is

Exception in thread "main" javax.ejb.EJBTransactionRolledbackException: EntityManager must be access within a transaction
 at org.jboss.ejb3.tx.Ejb3TxPolicy.handleInCallerTx(Ejb3TxPolicy.java:87)
 at org.jboss.aspects.tx.TxPolicy.invokeInCallerTx(TxPolicy.java:130)
 at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:195)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.aspects.tx.TxPropagationInterceptor.invoke(TxPropagationInterceptor.java:76)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.stateless.StatelessInstanceInterceptor.invoke(StatelessInstanceInterceptor.java:62)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:77)
 at org.jboss.ejb3.security.Ejb3AuthenticationInterceptor.invoke(Ejb3AuthenticationInterceptor.java:106)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:46)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:106)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.stateless.StatelessContainer.dynamicInvoke(StatelessContainer.java:278)
 at org.jboss.aop.Dispatcher.invoke(Dispatcher.java:106)
 at org.jboss.aspects.remoting.AOPRemotingInvocationHandler.invoke(AOPRemotingInvocationHandler.java:82)
 at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:734)
 at org.jboss.remoting.transport.socket.ServerThread.processInvocation(ServerThread.java:560)
 at org.jboss.remoting.transport.socket.ServerThread.dorun(ServerThread.java:369)
 at org.jboss.remoting.transport.socket.ServerThread.run(ServerThread.java:165)