SMC won't convert wmv video files to my fuze...

So I have SMC and I’m trying to convert a wmv file onto my fuze- but when i try it tells me that it “cannot be imported, please install the correct codec first. If the files can playback on your computer, probably Sansa Media Convert does not support this format, or the file is corrupted.” WTF? Do I need some additional software to make this work? (I have quicktime version 7, cuz i heard having this would help, but do I need something else?) Would it help to convert the wmv files to some other type of file? Or should I just use an entirely different program to convert my files? And if so what is a good program for this? Hopefully somebody can help, please???

I’ve only had luck with .avi files to convert.  I had to convert them first (using AnyDVDConverter) and then use SMC.  Espeically for long videos.