My dogs won't have puppies?

My dogs won't have puppies?

So in the sims 3, I'm running this crazy thing were I take people's neighborhood pets and hem in my backyard so they won't starve. I like having captors mate, so I'm trying to have two dogs try for puppies. I have pet houses ad stuff. T fit I tried in the backyard with the cheaper houses. I said try for puppies. They sniffed each other and their relationship went up, but they didn't do anything past that. I had to switch households to control the female. Her household only has five sims. Her mate is in a different household. His is full, but that doesn't matter if it's the male, right? I had this trouble with another one, but got them to breed on my lot eventually. I moved them to the front yard with the nicer house they still won't do a thing. What's wrong with them? (sorry that's so long XP)