Keep Alive Connection is not returned in response header by IIS 7

I am using IIS 7.  I am working on a MVC framework.
I am sending a request with a header "Connection = Keep-Alive" and the request is being processed and when i get a response , the Connection:Keep alive is stripped off.
I am using HTTP 1.1, the IIS has got Enable Keep-Alive Settings checked. If i uncheck this setting, my response has "Connection= Close"
Can any one tell me a way how to get Connection=Keep-Alive in response header with the settings Enable Keep-Alive settings checked in IIS7.
Thanks in Advance