Why wont my hamster sleep in her igloo?

So yesterday at PETCO I bought a igloo. I put tissue inside and she went on the other end of the cage and didnt sleep in it. I placed it on top of her and she stayed but she was asleep. Also she wont sleep in the little hidey house located in my habitrail ovo suite. (Right now im at my dads and i brought her in a plastic bin and input her in it becuase i forgot part of her cage, im going to cut a hole in the plastic bin and connect her habitrail cage to it)