If you are a user of SilverStripe too, I bet you have ever meet this kind of problem. What is your version of SilverStripe? Version 2.3.6? Higher or lower? Is this related? I guess so.. This is what I read in their forum.
Okay. This is my turn to speak. I am using SilverStripe Version 2.3.7, although actually you can found the 2.4.0 but I don't know where the file is. And the theme is wine.
After you unpacked the contents of the zip file into the /themes directory in your SilverStripe installation, then change to the themename...