Breeding Problem

I think I know what your problem is, Doffy! The reason why they aren't breeding is because Togepi is a baby Pokemon, baby Pokemon can't breed. You're going to have to evolve Togepi, with friendship. Items like the soothe bell, items that permanently boost stats, or spending time with him increases your friendship with him. To check your progress, talk to the girl with a Munna in the Pokemon Fan Club in Icirrus City. Let her check your Togepi. You can tell that he has max happiness when she says that your Pokemon likes you a lot and that she's quite jealous. Level Togepi up and he should evolve. They will be able to breed now. I had the same exact experience as you in Pokemon Pearl, I had remembered that Togepi was a baby Pokemon. I hoped I helped you with your problem!