Guess you solved the problem somehow by now, but many others still wondering how to solve it. I had problem pairing it in two occasions, hope this helps somebody:
1) First time I solved it opening the transmitter and took the battery out and put it back and it worked, first attempt paired.
Not sure if the problem was a bad contact in the battery terminals or if it makes a reset when new battery is places.
This time I had the firmware 3.03 in the computer.
2) I updated to the new firmware version 4.0 a week ago, also added a second transmitter.
I checked the "Set Dive" to see if I lost the pairing due the firmware update, but no, saw both transmitters paired.
By the time I went to dive, it didn't show the air, checked the pairing and noticed none of them were paired, tried 10 times with no luck, no way Jose.
This time, 2 transmitters can't be the same battery issue so I checked the documentation to see how to reset the computer make sure it boots clean, this worked and paired the first attempt.
Resetting the computer to factory default does not erase your settings or your logs.
To reset go to:
Settings
About Icon HD
Factory reset
While checking the net for an explanation of the pairing problem, I found this divemecrazy well done page which describes step by step how to do both things I described before, with pictures.
http://www.divemecrazy.net/how-tos/mare ... ansmitter/
To clarify, transmitter should pair the first attempt if computer is close to transmitter, if fails something is not right.
I use air integration since 7 years ago, had a Oceanic datamask and never had pairing problems, so something is still not right and Mares should do something asap, it is a expensive computer.
Regardless if this solutions make it work, we all should let Mares know about it and how disappointed we are and push them to fix it soon.