Truma ultra store/ultra heat

[Pennee]

I’ve just been for a look around the Swift Escape 696 on 2012 and has Truma Ultrastore and ultra heat controls. There were three and I managed to get two controls working but we couldn’t get the one for the warm air on. No illumination like the other controls and no heat blowing wether on low or high. Does anyone know what it could be or what we were missing. Checked fuses and they were fine in the sergeant. Also had water heater and all the other switched on at the seargent. I’ve never seen a model with three before and we were stumped how to get it going. It was in electric hook up but no gas but the book said it should work on both? Thanks