Why is my pet crab not mating with my pet lobster?

I bought both for the sole purpose of having them mate, but it is not working. Is it impossible for them to mate?
Answers

Anonymous

Because a crab is not a lobster, and a lobster is not a crab.

Eddie

No. Same as trying to get your dog and cat to mate.

M'aiq The liar

No, it's possible. But they may have no chemistry. For example, crabs really like siracha but lobsters hate spicy foods. Crabs love sports but lobsters prefer documentaries.