classcastException

hi friends,

I am doing one small project using Weblogic,Xdoclet,MySQL,EJB

nested exception is: java.lang.ClassCastException

I found that error is comming in the line
localObject = (NeworderLocal) home.findByPo_noCMR("91");

Where Neworder is the entity bean name....

EJBQL for findByPo_noCMR is

*@ejb.finder
* query="SELECT OBJECT(a) FROM NeworderSCHEMA as a WHERE a.po_no = ?1"
* signature="java.util.Collection findByPo_noCMR(java.lang.String po_no)"
*

please help me