IIS Configuration for Compression

Hi! I am busy looking into compressing .js files on a Mendix website using IIS. The type of compression that I am using is gzip. I then see that most of the .js files are successfully encoded with a server response of: Content-Encoding: gzip, however there are some files that don't have that response such as the ones found in mxclientsystem/. I have enabled compression of static and dynamic file types on the IIS6 server. Does anyone know why some files are chosen to be sent as gzip-encoded and some aren't? If so, how does one fix this so that all .js files are successfully compressed? Many Thanks.
1 answers

On the bottom of our howto on installing IIS in front of Mendix, there is a small section on compression. Does that help you?