it does not mean you have to use jdk 1.5, it means that that class was compiled with jdk 1.5 and jdk 1.5 compatibility and therefor needs 1.5 to run. Since the rest has no problems, It seems that the engine and the process are compiled with different jdk's. You could also recompile the specific class with 1.4 (e.g. set your eclipse ide to that) and redeploy the process. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4060586#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...