My male struggled with his ladder in his temporary hutch at first. I got a 3 tier hutch for him whilst he had to be seperated from my female, and he just couldnt use it. When i ordered the cage it looked better than when i got it however, the ladder is in a very silly place in my opinion, he has to get up the ladder and twist round at the same time to get onto the level.
He refused to use the ladder at first, so i locked him in one level to get him used to the cage for the first day. I then added the ladder to one floor, and placed water bottles, food bowls, hay and litters in each level, and he learnt to go down on his own, but not up. I kept placing him up and by day 4 he figured how to get up. Now, hes fine, he jumps up quicker than you can blink, but hes very small, my other rabbits probably wouldnt be able to.
Aslong as the ladders in a good position and its wide enough, then you may just have to teach them how to use it, that is if they dont pick it up right away. I placed veg and treats on the rungs of the ladder, and thats how mine eventually figured it out. Just make sure you provide hay food and water on the bottom level until they can definately use it ok.
Simon gave me a tip for mine which i was going to do, but didnt need to in the end- of using roofing felt to provide extra grip on the ladder, although some ladders have a similar thing on them. Good luck!