Problem while returning service data

I could return ecore based items from service but when I try to return a custom type (a java class that I have defined) from the service, I could not succeed and I get the following error.


"errorClass":"java.lang.ClassCastException"
,"errorMessage":"com.ibm.team.af.research.userextension.common.FeasibleSchedule incompatible with org
.eclipse.emf.ecore.EObject"}


Any help? Is there any restriction that every thing needs to be based on ecore?