Perhaps an easy question

From my desktop, I am able to connect to an internal website on port 80 using my cache login credentials.. whether you want to call this cached credentials, pass through authentication, windows integrated authentication, I do not care. I pull up the browser, i hit the page, I'm in.

 

 

When I try to hit this same website going through the VIP address on the F5, I am prompted for a second login. I need to find a way to resolve this. The F5 is either dropping/stripping some information, I am missing a setting on a profile, or something is missing on the ISS server. Thoughts?