Dynamic compression doesn't seem to be used in IIS 7.5

Question

I currently have both static and dynamic compression configured. The static compression is working, however the dynamic compression, when checked through YSlow and Fiddler,

Answer 1

Are you sure you have Dynamic Compression installed in IIS? By default, it is not installed on Server 2008 (or R2). Try this article: http://www.iis.net/ConfigReference/system.webServer/urlCompression

Answer 2

Check this thread, it sounds like you are having a similar issue:

How can I get gzip compression in IIS7 working?