Remote key not working

I have 2 remotes for the 2004 A4 Audi. One works fine while the other one shoots blanks. Changed out the battery... no response. Tried to reprogram with the good remote in the ignition turned one click to see the display light up. Placed the bad remote key in the drivers door and manually locked the car. Then pressed the unlock button.... no response. Tried the same steps but reversing the keys. Good key in the door. Still no response.

Am I leaving a step out of the process.

Thanks, Steve