Assertion Failed EJB.. weblogic

I have an Ejb deployed in weblogic61 and one of the methods is exposed as a service in webmethod,The bean method returns an user defined object. I have the jar file with the user defined objects put in the code/jar dir of the service in webmethods also. When I run the service I get this error in statusMessageMethod0 attribute of the call.

EJBServices.invokeEJBMethod - beanWrap.invokeMethod threw this: type(com.wm.pkg.ejb.EJBException), msg(; nested exception is:
weblogic.utils.NestedException: ***** ASSERTION FAILED *****[ Exception creating response stream ] - with nested exception:
[weblogic.utils.AssertionError: ***** ASSERTION FAILED *****[ Exception creating response stream ] - with nested exception:
[java.io.InvalidClassException: com.arrow.domain.user.UserVO; Local class not compatible: stream classdesc serialVersionUID=2835897757001519106 local class serialVersionUID=-7978473912484034509]])