request.getParameter("Login") returns null in servlets

I am using applets embedded in html and applets forwards to servlet.
In my Login Servlet req.getParameter("Login") returns null at a few places always.
I just upgraded to Java 1.6_027 from 1.5_06 and Weblogic from 9.1 to 10.3.5
My code use to run fine before the upgrade.no changes in code are done but now req.getParameter("Login") retuns null
at a few places.I am fetching the request.getParameter in the doPost method and calling the doPost method from doget method
Please help me out to figure out what could be the issue.

Thanks

make sure that the "Login" is right not "login" and the parameter's value of login is not null in applets