Can't use dom4j. Class org/dom4j/Document violates loader co

[nigelwhite]

I'm getting the error:

08:54:07,109 ERROR [fcl] java.lang.LinkageError: Class org/dom4j/Document violates loader constraints
08:54:07,109 ERROR [fcl] Error source /gfFw/MenuBuilder.jsp
08:54:07,109 ERROR [fcl] Exeption in /gfFw/MenuBuilder.jsp
java.lang.LinkageError: Class org/dom4j/Document violates loader constraints
 at org.apache.jsp.MenuBuilder_jsp.updateUserMenu(org.apache.jsp.MenuBuilder_jsp:74)

I have put the latest dom4j jar in WEB-INF/lib

What does this error mean? I need to use dom4j.

[nigelwhite]

It's OK, dom4j doesn't implement the DOM3 methods in the JRE 1.5 libraries. We can't use it! :-(