Yeah! you are absolutely right!!! it was cause by the aopc version differentce. The story is like this: I put all my jar libs in a so called extlib library which included jboss-aop-jdk5.jar. The problem is that somehow my colleague put some of their jars in there too, one of which is for jboss client and it has the same name jboss-aop-jdk5.jar too but actually they are from different version. I know this but checking the MANIFEST.MF in the META-INF of the jar. My colleague's version was : Implementation-Version: jboss-aop-1.5.2.GA Mine was: Implementation-Version: jboss-aop-1.3.5 And somehow in Eclipse classpath my colleague's file was listed before mine that's maybe why it use that one to run the project and cause the error. I solved this by adding my aop jar to the classpath and re-order it to the appear before all jar and now the problems gone. Thanks a lot Kabir! View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4049170#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...