I've been trying to get a Riolu for Black 2 so instead of looking for one, I decided to breed one with amazing Attack stats and knowing the move Blaze Kick. I choose Blaziken for the male and Lucario for female, but the two won't give me an egg. They are both part of the "field" egg group so they should breed right? Am I doing something wrong?
Yes they should be able to breed, but it is a random chance depending on what the daycare man says. If he says anything else besides "The two prefer to play with other Pokémon than each other." Then you Pokemon will breed. It may take a while but be patient.
It all depends on the egg cycles. There is the CHANCE of an egg being created every 255 steps, but not a certainty. The chance is higher if the Pokemon are more compatible, and you can check that by going to this website