Hi,
there might be some reasons for this:
-your client app contains JBoss jars which do not match the jars of your server.
-your client app contains older versions of the class files of your EJBs/EJB interfaces (either from an older compilation, or e.g. compiled with a different JDK version).
By the way: how do you develop your app? Do you use some IDE? You are running in a whole lot of errors which would probably not happen if using e.g. "Eclipse for JavaEE developers".
Best regards
Wolfgang