Ah, this is such a common problem with everyone. I have had this problem several times and the way I fixed it was to either just reboot and hope it applies the theme or else unload windowblinds, change your window appearance back to aero or whatever and reboot and then load windowblinds again. This only happens to me randomly about 1 in 50 times but there are ways around it.
By the way, Im running vista ultimate 64 bit.
Hope this helps a little. Also, you can refer to this post.
https://forums.wincustomize.com/342989
