I think I may have found what can be the main cause for most people not getting certain channels (premium channels for example) through their cablecards.
In short, if the signal strength of your cable line is not enough, the "hit" your cable company sends to your cablecard might not register. Increasing the cable strength solved the problem.
The long story:
A tech from Charter Communications came in for my initial install, put both cablecards in programmed them and went on his way. After I finished the guided setup, I noticed that:
1. Cablecard1 was not getting HBO, Discovery-HD, ESPN-HD, HDNet (premium channels).
2. Cablecard 2 was ok getting all the channels.
I called Charter, and they verified in their computers that both cards are identicial in the "codes" they have, ie, they are both authorized to receive all these channels. She sent a "hit" to my cablecards again and asked me if it worked, but no dice.
We setup an appointment with a technician to come over. He came today with a brand new cablecard, removed cablecard1, and replaced it with the new one, called it in, got it programmed, we got the "hit" but no dice again, no premium channels.
We tried numerous times to send a "hit" from the cable company, and in the cablecard menu it said AUTH RECEIVED, but no dice every time on the premium channels (we even waiting 30 minutes).
Then a thought occured to me. The signal from the main cable line comes to a three way splitter, and one of them goes into the TiVo and spits again (for the dual tuner).
I asked the tech to check the signal strength (it showed OK via TiVo). The tech used his own device to check to strength and it turns out I had very low signal strength. I changed the three way splitter into a two way, and he modified some lines in the house to increase the strength, then we called it in, and when we got the "hit" this time it took.
That was it, the signal strength was initially not enough to program the cablecard...