Inherits properties from unknown version

[CameronD]

So my modded minecraft doesn't work and every time i try to start it up it gives me this,"The version you are trying to play inherits properties from an unknown version". I read somewhere that this can result from running the inactivated windows which I did for a couple months but I activated mine about a month ago and it still doesn't work. I have deleted twitch and minecraft but the problem still happens. When i delete minecraft there is always one file that wont delete so that could be the problem but I never went after that. I am trying to play FTB Revelations through twitch and I built my pc.