My SECURITY light flashes when I open the door and I can't program a new remote. on 2002 Chevrolet Silverado 3500

I have a 2002 Silverado 3500 that has a blinking SECURITY light that comes on in the MESSAGE CENTER when I turn off the vehicle and open the door. Yesterday I tried buying a pair of OEM key FOBs, as mine didn't have any when I bought it from the guy a month ago, and during the programming process where you are supposed to hold down the vehicle UNLOCK button while cycling the ignition on and off
twice, then let go of the switch and it is supposed to lock and unlock
itself, thereby indicating that the truck is in "learn" mode, nothing
happened. After I cycle the ignition twice and let off of the UNLOCK
button, nothing happens. Therefore I am unable to program the key
FOBs...Please help.

1 answer
Try this
http://www.wikihow.com/Program-a-Keyless-Entry-for-a-Chevy-Silverado
or
http://wiki.answers.com/Q/How_do_you_program_a_keyless_remote_for_a_2001_Chevy_silverado
or
http://programyourremote.com/classified/DisplayAd.asp?id=354