Actually, your code is lying to you! You asked it to say "Not found" if the find result is different from -1. However, a find result different from -1 means it did find something. It only returns -1 if a result wasn't found.
In your case, find should return 8, since the FF0000 string starts, I believe, in the eighth character. If all you need is to know whether the bbcode exists in the code or not, it doesn't exist if find returns -1, and does if it returns anything else whatsoever.
Good luck :)