Thanks for your hint. Searching for files referencing the "jpdl.xsd" give no results. But while searching for the files I found out that the "jpdl.xsd" was not available in the classpath. So I made it available in the classpath, but this didn't resolved the problem. . Now I focused on the classloader and change the behaviour of it, to prefer the classes in the WEB-INF folder. And voila, everything works fine. it seems that some libs deliverd by the weblogic server are not compatible. For all people also deploying on a Weblogic 10.3: In detail I added the following lines to the "WEB_INF\weblogic.xml" file : <container-descriptor> <prefer-web-inf-classes>true</prefer-web-inf-classes> </container-descriptor> Now I'm facing another problem. but for this I'll open another thread, after some more researches. thanks and best regards sirfrancis Tom Baeyens wrote: