Dynamic compression does not work with WCF

I tried to configure my virtual machine with windows server2008 r2 to allow dynamic compression, but that is not possible. I followed the directions of the link:

http://www.hanselman.com/blog/EnablingDynamicCompressionGzipDeflateForWCFDataFeedsODataAndOtherCustomServicesInIIS7.aspx

I'm usingWCFwithFremework4.0
Any idea how to enable dynamic compression en IIS?