taskdef class org.apache.catalina.ant.deploytask cannot be found
I am trying some examples of webserives. These examples are required to be run by Ant tool. Now I intall JWSDP-2.0 and tomcat50-jwsdp separately. And set up enviroment variable. now run Ant to compile the program, displays an error-----D:\CIS631\JWSNutshell\examples\chapter1\amazon\buildsetup.xml:31:taskdef class org.apache.catalina.ant.deploytask cannot be found. I have no any idea for this error. Who could tell me how to solve it? Thanks for your help!