Proteco gate code remotes

[stroller]

Hi I have a proteco advantage unit opening double gates, it stopped working yesterday but I got it going again by cleaning the photo cells, unfortunately all the remote key fob codes seem to have been lost. I have tried to reprogram them but I can't get the unit to accept them, I am following the instructions to the letter, the red 'full stop dot' that should appear when I press button C and the remote button won't light up and the code is not accepted. The gate works fine on the key switch, I have tried 4 different fobs and they are all the same. Help!