My Hamster doesn't know how to...climb

[PrincessMargot]

So, my Robo Hamster Algernon Loves to burrow! So I decided to add a burrow box in his cage, but then while watching him investigate the mysteries box I realized he couldn't climb. I pick him up and put him on the ladder to see if he would figure it out but he just looked at me like "what am I supposed to do" and he jumped off the ladder. I don't have enough room for steps so I can't just add steps. I think the problem stems from where I got him and his first cage. In Petco he had his igloo and a wheel (nothing to climb! And in my first cage he had more things like a sand bath and more hideaways, but even then Algernon could just lift himself over edges, and I had more tubing systems and less climbing things. What do I do to help him climb?

Thanks!