[Closed] Disc rotor compatability

Recently bu*****d my Formula rotor on my ORO brake set. I had and Avid equivalent 160mm one, so decided to use that as the flat profile looked fine. However since putting it in, my rear brake howls constantly like a banshee. There is no horrendous rubbing and the wheel spins as freely as before. Not perfect, but a slight binding thats not significant enough to worry.
Just wondered whether the clearance is an issue, I cant remember whether the rotor is thicker or something, and maybe it will settle down ? Or is not compatible