Startup servicenot loading

There is a situation where we’ve migrated a package from wM 4.6 to wM 6.0. Apparently everything works fine except the start up services are not loading. These are java services and i am able to compile them thru the developer. Following error is thrown while the package is reloaded during the start up of the services
java.lang.NoClassDefFoundError: com/wm/app/b2b/server/ContentHandlerFactory

The above is a class in server.jar and it is there in the server’s classpath. Thats the reason i am able to compile the startup services without java.lang.NoClassDefFoundError exception thru developer…

I am not sure what is missing…

Thanks in advance for your help