Be careful, which version of Seam you are using: The one atao is using is for Seam 1.1.6 whereas dustismo´s is for 1.2.0. But as far as I can see from the exception you simply did not include the trinidad-jars properly. Check if you´ve got both jars, the "impl" and the "api" and also include them in your manifest.mf of your jar. Thomas View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4024658#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...