1998 Blazer Keyless entry

[cannon73]

I have a 1998 Chevy blazer with keyless remote. I have two remotes that work already but I wanted to add another. I tried Transmitter Programming:

1)With the driver door closed, hold down the power unlock button on the door panel.

2)Turn the ignition switch to the ON position

3)Turn the ignition switch to the OFF position

4)Turn the ignition switch to the ON position

5)Turn the ignition switch to the OFF position

6)Release the power unlock button on the door panel.
The remote control door lock reciever will respond in the following manner in order to indicate that the receiver is in the programming mode:

6.1)Locking the doors

6.2)Unlocking the doors

IMPORTANT:
All extra transmitters must be programmed at this time. When a new transmitter is programmed it will deactivate the old transmitters.

7)Hold down the lock and unlock buttons on the transmitter until the remote control door lock reciever will respond in the following manner:

7.1)Locking the doors

7.2)Unlocking the doors

8)Repeat step 7 for each additional transmitter

9) Turn the ignition switch to the ON position in order to exit the transmitter programming mode.

But the door locks do not respond (does not go into programming mode). If anyone knows what the problem is and the correction please let me know.