replaced the ignition lock...security light only comes on when I am tr

I replace the ignition lock on my 2004 Chevy Silverado becouse of an issue with the old one getting locked into the start position and battery had gone dead. Ounce it was replace it the security light only comes on when I am trying to start it but then it goes back off when I stop. When I tried to reprogram the new keys the security light only comes on when the key is turned on and only for about 20 to 40 sec. And then it going off. I have tried to reprogram the new key 3 times now with turning the key on and waiting 10m then turned of for different times between each cycle of the 10m key on. The first time I did key off and key right back on. The second time I waiting 5sec between each key on and the third time I did 10 sec. Between key on cycle and I am still not getting any kind of engine cranking just the security light comes on.

Can someone please me out on what it is that I am doing wrong with reprogramming the new keys