.wmv doesn't play in powerpoint even with flip4mac

hello everyone,

i'm fairly new to macs and i hope that you can help me. i have to do a presentation for university and did that on my mac in openoffice. however, at university they only have windows systems, so i converted the videos for that presentation to .wmv on my dad's laptop. everything is working perfectly there, but on my macbook the videos just won't play. i have installed flip4mac and the video files themselves play perfectly fine. only the ones embedded in the powerpoint don't. i see a screenshot of them in the presentation, but can't start them. anyone know how i could solve this?

thanks so much in advance!