Now I've got the gas sorted I thought I'd move on to the electricity

.
So, Bambi came with an orange lead and blue plugs and I bought the adaptor so I could plug it in at home. Plugged everything in this afternoon and flicked the first two switches down and the orange switch down on the zig unit (cf9b). The red "low" battery light came on and stayed on for the rest of the afternoon. I gave it up as a bad job, unplugged everything and came in to read the manual

. Realised that I should've had the charger switch flicked down too so went out and plugged everything in again and tried that. Battery light still
red even though according to the manual it should be
green while charging even if the battery is flat.

Am I doing something wrong or is it not working properly?
The little strip lights work whether plugged into the mains or not, so the battery can't be completely dead.