Unable to convert string "true" to class "javax.el.ValueExpr

[johndoe123]

I managed to extend the ExtendedDataTable and create a custom component, but now that I want to add attributes, I always get this error-message:

org.apache.jasper.JasperException: Unable to convert string "true" to class "javax.el.ValueExpression" for attribute "sortable": Property Editor not registered with the PropertyEditorManager
 org.apache.jasper.runtime.JspRuntimeLibrary.getValueFromPropertyEditorManager(JspRuntimeLibrary.java:887)
 org.apache.jsp.index_jsp._jspx_meth_tmg_005fTmgColumn_005f0(index_jsp.java:193)
 org.apache.jsp.index_jsp._jspx_meth_tmg_005fTmgDataGrid_005f0(index_jsp.java:162)
 org.apache.jsp.index_jsp._jspx_meth_f_005fview_005f0(index_jsp.java:121)
 org.apache.jsp.index_jsp._jspService(index_jsp.java:83)
 org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
 org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
 org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:322)
 org.apache.jasper.servlet.JspServlet.service(JspServlet.java:249)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
 com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:410)
 com.sun.faces.application.ViewHandlerImpl.executePageToBuildView(ViewHandlerImpl.java:468)
 com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:140)
 org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:100)
 org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:196)
 com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:110)
 com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
 com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
 javax.faces.webapp.FacesServlet.service(FacesServlet.java:266)
 org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:177)
 org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:267)
 org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:380)
 org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:507)
 org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)

Most posts on the web say it's got something to do with dependencies, but I tried lots of things in vain and can't figure it out.

My CustomTag just extends the ColumnTag:

package myPackage;

import javax.faces.component.UIComponent;


public class MyDataGridTag extends org.richfaces.taglib.ColumnTag
{
 @Override
 public String getComponentType()
 {
 return "MyDataGrid";
 }

 @Override
 public String getRendererType()
 {
 return null;
 }

 public void release()
 {
 super.release();
 }

 protected void setProperties(UIComponent component)
 {
 super.setProperties(component);
 }
}

Shouldn't it inherit all attributes from ColumnTag and automatically use them? There're no problems using the richfaces ColumnTag with my custom component, just my inherited version causes problems.

Please point me in the right direction.