Help asap!! for hamster lovers,breeders,vetsanyone who knows about hamsters!?

ok so around christmas a i got a girl blck bear hamster and just 2 days ago i got a teddy bear hamster and i want to mate them so i can sell the babies. well they havent fought once they get along just fine in there cage it seems like they dont even no each other is in the same cage. but when i put them in there mating box they just curdle up in a corner and fall asleep. and in there cage they just ignore each other. the girl is around 5 months and the boy is around three and i just want them to mate whats wrong and what do i do to make them want to mate?