ssloffload for IIS but can't used http profile

I repeat the problem

 

I had two IIS servers，and SSLofload used for IIS ,I had used SNAT。Now，the customer want to IIS log client real IP，so I want to use x-forwarded-for 。Then，I creat a http profile，and select it for the VS（there isn't had any http profile early）。But the problem is coming。I access my site，I receive a message “you are confined to access the site”by IIS，and if I take of the http profile ，the problem is gone。so I don't know why。