sims freeplay cat wont go upstairs

So I brought a cat and put it in a two storey house, but it REFUSES to go upstairs. 

I call it up with a bowl/bed/scratching post, and at most it will stand up, but it won't climb the stairs and just wonders of. The stairs are straight ones, and they're not blocked, my sim uses them fine.

My dragons and fairy's use the stairs fine, but when I tried my dog he wouldn't  climb them either. I REALY need to get my cat upstairs (the sims who owns her lives on the second floor), so can anyone help? Thnx