Problems Using Request.Querystring

I'm using request.Querystring to redirect the user back to the original page after logging in. The querystring redirects them back to the orginal page, but the login session is not updating, so it redirects back to the login page. I tried a link that will go to that page, and when the link is clicked, the session is logged in, and works fine, but when I use the querystring as a link
(<a href='<%= Request.Querystring("location") %>'>Continue...</a>), just like before, the login session is not updating, and will redirected back to the login page. It has worked a couple time in IE but never not Firefox and not always in IE. Is there a way to correct this?