every time i try to use this one skill i bought, it gives me an error message. I tried charging RP, and it didn't change. and i used other buffs thinking maby it'll work after. but no luck. I'm guessing i have to use some sort of weapon or something to get it to work.. but if anyone here can tell me what i need to do that'd be great. thanks in advance.http://imageshack.us/f/802/errormessagea.png/

Edit: nevermind, i found out what it was.