my quantize won't work

Hi! I recently installed and am using Pro Tools 10 on my new desktop computer and every time I quantize a set of midi notes it doesn't play back with the chosen instrument afterwards. So it plays beforehand and not after quantizing just plays a weird drum set sound? Help? I am using a performance synthesiser keyboard to play it but this shouldn't be the problem. Its something in Pro Tools 10 and Xpand 2. Please help?