Servlet Request Processor Exception in web sphere 5.0

[app yadav]

Hi,
I am trying to deploy a web application[mywar.war is the name of the war file which i m deploying on server] on Web Sphere 5.0 ,it gets installed properly but when i give the request from the browser as
http://localhost:9090/MyWar/welcome.jsp
then it gives me following error msg:
"Servlet Request Processor Exception: Virtual Host/WebGroup Not Found : The web group /MyWar/welcome.jsp has not been defined"
where /MyWar is the context name.
So can any one pls help in this problem..
Thanks in advance..
Aparna