ClassNotFoundException for test classes

Hello,

I try to run cactus tests on Weblogic 8.1 and I get a
ClassNotFoundException telling the test class cannot be found.

I've seen many threads about this and it always appears that the test
classes where missing either in the WEB-INF/classes of the cactified war,
or in the classpath on the client side.

I ckecked that (by echoing the classpath in my ant build-script and 
viewing the content of the war file on the server) and the classes are
present on both sides !


Any hint would be greatly appreciated.

Many thanks,


Pierre M.