Just to make sure, after you press and hold the program button and the light starts blinking, you then first press the keypad button you want to program and then send the X10 codes, right?
I'll be at my other place this weekend where I have some of these, albeit they're 10 years old, so I'll try programming one to see exactly what works. I'll try with a mini-controller even though I've always used a maxi.
One other thing. Before you try again, pull out the programming button all the way till the LED goes off, then push it all the way in to get into programming mode.