My rats and their new cage?

Okay so we built my rats a cage. It has four levels and wooden ramps that leads to a openign to the next level of the cage. My concern is that they cant figure out how to get to each level. The bottom level doesnt have anything in it yet bout 2nd was food and water 3rd was toys 4th is housing. I was concerned about them being to scarred to leave the house level (b/c they were only in a one level cage before) and not being able to get to their food and water, so i introduced them to each level and let tem hang in each before moving them else where then placing em back into the top floor but they make no attempt to try to explore the other rooms. Right now i have placed them on the second floor with food and water so if they cnt figure how to get up and down. Will they figure out how to explore each floor? oor not??