Sorry I haven't gotten back to you. Had to use my resources to make sure I don't give you any bum advice. I have run into this before on another car, and couldn't remember exactly what car it was and what I've done to repair it. Looking back, it was an 04 Lancer and no RKE transmitters could be programmed. I ended up replacing the ETACS-ECU and it solved the problem. Although the ETACS is different, the 04 Lancer uses the same transmitters (Omron) as our Evo's and the operation is basically the same. Are there any aftermarket accessories installed in your car that might be interfering with the signal? Are you certain that your transmitters are all functioning properly? Do you have the correct transmitters? Omron transmitters A, B and C are interchangeable with each other, but Denso and CodeAlarm transmitters are not compatible with the Evo. So, what to do?
If you have access to another Mitsubishi vehicle that uses the same transmitters, take your transmitters and try to program them to the vehicle. This is the quickest way to eliminate the possibility that your transmitters are at fault. At the same time, take the working transmitters from the other vehicle, and see if they program into your vehicle. If you determine that your original transmitters are functioning, then you are looking at an ETACS-ECU problem... Do this, and please let me know what you find. As I mentioned, ETACS problems are not common, but possible.