Can't play .wmv files...

Hi list, I already have installed both Kaffeine and MPlayer but I can't watch .wmv files. The MPlayer FAQ says something like "install the latest plugins" so I did... the last ones installed under /usr/lib/win32 belong to the "essential-20040427 collection"... but as I said, it's not possible to play .wmv files at all... Any suggestions? TIA, Martin