My webApplication works just with TOMCAT 3

Question

I've done a web application server/client.
It's a Servlet and an applet.
I developed that app with tomcat 3 but with tomcat 4 it does not work.Why?
I tried to use the manager servlet of TOMCAT 4 for deploing but after installing the web appplication it does not work.

Answer 1

It 's better but maybe you can help me with this problem.
I have this web.xml on my web-inf folder:
<web-app>
<display-name>Server Application</display-name>
<description>
     This is a simple web application with a source code organization
     based on the recommendations of the Application Developer's Guide.
</description>
<servlet>
<servlet-name>EchoServlet</servlet-name>
<servlet-class>EchoServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>EchoServlet</servlet-name>
<url-pattern>/MM2</url-pattern>
</servlet-mapping>
</web-app>
The problem is that Tomcat 4 cannot find the url pattern /MM2 and so my Servlet.With Tomcat 3 it works.
I configured the server.xml and web.xml (not the web-inf/web.xml) as the http://www.moreservlets.com/Using-Tomcat-4.html#Enable-Invoker
author suggested me to do.And with these new features some easy Servlets work correctly.Except my servlet with the url-pattern above specified.Help please!