I have had the best luck by extracting the zip files on the pc, then copying the extracted theme file to the sd card theme folder. Then "pick a theme" in MM.
The best way to trouble shoot the themes is to pull/copy the appropriate .apk from your phone to the pc. Rename to xxxx.zip, and extract the contents. Then you can go through the themename.thm file (Notepad++) and see what it is trying to replace. Open up the res/drawable folder in the extracted theme, and do a side by side comparison to check that the folder/names paths correlate exactly, and that the names of the images (.png) correlate exactly between the theme files and the files pulled from the phone.
This really is the best way to troubleshoot, as depending on which .apk you are trying to theme, you could have a slightly different version than what the theme was built around.