Bunnies in the wild have their breeding season when there is more light, so the same can probably be said for domestic buns.
Maybe they are not getting enough light for the doe to realise that itis a good time to breed. Some breeders put a certain type of light (I'mnot sure what though, so hopefully someone else can help you there) inwhere the bunnies live, so that they think it is a good time to breed.Maybe doing something like that would help.
Also, when you put them together, how do you do it? I found my doe morereceptive if I enticed her with his scent before actually putting themtogether. Soemtimes doing this by swapping them in their hutches, orswapping toys, before putting them together.
When they are together does she run? Her running away from him and alsorunning in circles gets the doe going, so do they have enough space todo that?