I Used the codes for the H-10 in the database, they worked perfectly for me. I had the same trouble with an MRF 300 though. Emmitter output strength on all six outputs is the same on the MRF 300. It's the H-20 that is the problem. It's being oversaturated. Black electrical tape with 2 small holes punched in it worked for me. It took 4ever, but i got it!
Don't forget to turn the IR off on the remote.