diablo 2 hex editing

i'm using the program HexEdit for mac os 10.2, whenever I change the stats on a character it won't let me play a game as that character, it says "unable to enter game, generic bad file" what did I do wrong?

ya it use to say that for me just delete the char cause it would be too hard to find what u did wrong but u can download a char so u can make it so godly and they come wit items so just downloas one and try and read before u screw it up again

i do not know