Hamster Has Problems Becoming Pregnant

I have two golden hamsters and their both 6 months old. They've been in the same cage for 2 months now and she's still not pregnant. Is there any thing else I can do to get them to mate. Is there a certain age to breed hamsters and how would you get them to breed.

The females come into season for at least 4 hours every 4 days throughout the year, and immediately after giving birth. Being nocturnal, they are likely to be receptive to a male only at night.

Even experienced breeders don’t know a definitive way of telling when a female is in season. However, one would expect that having been together for two months that they would have mated already. Have you considered that they might be the same sex? The age of the hamsters is just about right for breeding.