I would try redownloading it first. Maybe just a bad download. Probably not but best to rule it out now. How are you trying to link it to FSX? I don't know the in's and out's of Win 8, I use Win 7 but try running as an administrator either way. I have Admin rights on mine as well but sometimes I still have to force the issue. Hope any of this helps! The weather in this program is well worth it!