have ur door card off and check the positioning of the motors, if they open all the way/close all the way and thers resistance they will close/open again..... take one off andactivate the locking and if it does it still then take the other off and see if still does it. if it works perfect wile ther off you just have to realign them when fitting them back up.
if thats not your problem im not sure what to suggest.