irule/apm/redirects

we are replacing our MS ISA servers with a F5 login screen. everything was working geat until one aspect was missed.

 

the site is https://www.mysite.com

 

a user sends a link to http://www.mysite.com/something.pdf

 

the end user gets redirected to the login page adn once the credentials are entered. they get a page not found.. but if they click on the link again, it works..

 

how do i make it such that once they enter in their credentials the redirected site appears?