What is your provision for error handling in the code which calls the web service?
There are so very many things which can go wrong in creating and dispatching a
SOAP request that you need to catch errors as close as possible to the code causing the error.
The "Caused by:" message sounds like you are letting Tomcat catch an exception rather than handling it in your own code.
Personally, I would put all web service calling methods in a "helper" class which could be tested outside the
servlet environment and get that running before attempting to build it into a servlet.
Bill