为什么浏览器在部署后不显示favicon

I have a asp.net mvc web application an it uses some favicon.ico. Now when I move it to IIS 7, as an application, the favicon stops being presented even when I try to enter the full address to the favicon. The icon is still there; the full address works in the browser to find the icon alone, but not within the applications master page. The code is standard and same as on some others of my apps, but there it works.I have a asp.net mvc web application an it uses