As far as I am aware on the Ford KA up to 2008 they still use the Z4C chip. If using the zed bull you must use the Z4C chip as the KA does not for some reason like the TPX1 transponders. Also check the key that you are using if the transponder is not close enough to the transmier on the vehicle this may cause the problem that you are having. I made sure that the transponder was pushed as far into the insert on the key.