When you re-program the remotes and the keyless entry do you hold the smart (learn) button or do you press and release it?
If you hold it you are erasing all of the previous codes. If you are just pressing the learn button and immediately releasing it and then pressing and releasing the button on the remote and they still will not take a code then you need a new circuit board.
On the back of the motor where the learn button is you will find the number for the circuit board, it starts with 41A****-**. I hope this helps any problems you have.