A Question about Xerces parser

[Anping Wang]

What would cause the following error

Generated fault:
  Fault Code   = SOAP-ENV:Server.Exception:
  Fault String = java.lang.AbstractMethodError

This occurred when the service uses a third party parser to construct a dom
element that will eventually return to the client. Please note that the
service works fine if an Xerces parser is used.

Thanks for your help in advance.

Anping