Single sign On with JAAS

Has anybody ever implemented single on using JAAS? I refered to this article on devx.
For supporting single sign on it uses an option, Shared state map in login config file. this options is
used for passing user security information between login modules.

If the attribute useSharedState is true, this LoginModule retrieves the username and password from the module's shared state, using "javax.security.auth.login.name" and "javax.security.auth.login.password"
as the respective keys. The retrieved values are used for authentication. The username and password are set into shared state by LoginContext before invoking the login method of the login module instance. The useSharedState attribute allows all login modules to share the user's credential information, which is captured only once.

However, when i tried using this option,it did not help me much. Everytime i try to authenticate the user, it does not retrieves
the username and password from the shared state map. rather a new instance of login module is created which does not have shared
state information. so single sign on cannot be acieved.
can anybody help me in this respect? any help would be highly appreciated.
[ March 16, 2004: Message edited by: Rashmi Tambe ]

Can anybody answer this please???/