ClassCastException while usng getServlet(String)

I am using the following configuration 
 
a) Jigsaw Web Server from w3c Consortium that supports Servlets
b) JDK1.2 beta 3  
 
I have two servlets
 
1)   MxSessionManager    servlet
2)  MxBrowse servlet 
 
User invokes MxSessionManager first. This gets inited allright. Then user invokes MxBrowse servlet. Within MxBrowse init method, I want the reference to MxSessionManager instance. MxSessionManager maintains session details which is required each and every subsequent servlet call. I am getting the referenc as given below
 
ServletContext sc = conf.getServletContext();
MxSessionManager sm = (MxSessionManager)sc.getServlet("MxSesssionManager");
 
This gives me ClassCastException. I have checked the Class object of the returned object of getServlet("MxSessionManager").
This is shown the same as MxSessionManager.  
 
Option 1 tried
--------------------
However, if I cast the returned value to HttpServlet, or GenericServlet the superclasses of MxSessionManager, then there is no 
ClassCastException. 
 
HttpServlet hs = (HttpServlet)getServlet("MxSessionManager");    // works fine
 

Option 2 tried
--------------------
 
I have tried subclassing MxSessionManager say as MxLogin extends MxSessionManager. Now I do 
 
MxSessionManager sm = (MxSessionManager)sc.getServlet("MxLogin");
 
still no use.
 

                            ------------------------------------------------Code Snippet -------------------------------------------

public abstract class HttpServlet extends GenericServlet implements Servlet {
......
}
public class MxSessionManager extends HttpServlet {
........
}
public class MxSessionHttp extends HttpServlet {
      public void init( ServletConfig conf ) {
try {
     super.init( conf );
} catch( ServletException e ) {
} 
 try {
      MxSessionManager sessionManager = (MxSessionManager)
  ((conf.getServletContext()).getServlet("MxSessionManager"));
} catch( Exception e ) {
************ I am getting ClassCastException here.  ***********
}
    } 
    .................
}
 


Can someone help please? 
Thanks