can't play wmv file on quicktime?

I can't play .wmv files on quicktime. I installed both QuickTime MPEG2 and Flip4Mac WMV hoping that this would solve the problem but it did not. When trying to play any audio .wmv file I get an error box stating "the document (filename).wmv could not be opened. The movie is not in a format the QuickTime Player understands. You may need to install additional software to open this type of file". Anyone know what I might need here?