95 Tahoe Keyless Programming Mode

I have bought replacement/spare Keyless remote transmitter (2) but can't get into the programming mode.
I have grounded (to - on battery and on the engine) jumper G on the data link connector but nothing happens indicating programming mode. I have tried pressing lock on the new remote - nothing! Took the jumper of and my old remote still works. I have changed batteries on the remote and checked the new ones with a tester.
I'm at a loss :confused:

Are you turning the ignition to ON (not engine on) after you connect the paperclip?

I have tried with ignition on, offf and accesories only and nothing seems to get it in programming mode. I have tried grounding several places including on the manifold.
You mentioned a paperclip?? I have grounded by running a 12 gauge solid wire from Jumper G on the DLC. Are you suggeesting using a paperclip between two jumpers on the DLC.?

Any suggestion - am I overlooking something?

Yes, you can insert the ends of a paper clip in each terminal to ground them as instructed.