I've tried my optimate on 3 motorbike batteries..

When I plug it in, all it shows on all 3 is the AC #1 light.. is there a chance my optimate (almost brand new) is faulty, or are all 3 batteries non repairable? I've tried switching the cables to the wrong terminals, to see if it would show light 2 but it doesn't recognise it's on the Wrong way either?