If your just trying to do random feints to play mind games then you should use the seismo feint instead of the TK feint, I think its easier then random TK feints unless of course you attack then feint, so cr.mp xx feint for mind games.
EX TK probably means you are doing the second input too fast. Possibly there might be some negative edging at play as well. Try cleaning up your button presses and start with lp tk feint. The timings are pretty specific per strength of knuckle, but lp has the most leeway and is easiest by far.