Picky Male or Girl Just Not Ready?

Well, my pastave boy has been locking like crazy with my pastave girl. Put him in her tub and within an hour, they'll lock. Put him in with my albino girl and I've seen 2 locks over the last couple months total. I've found them close (tail against tail but no actual lock) multiple times and she doesn't seem to be avoiding him. They just seem... indifferent. Is it possible she's just not ready? She's a 2011 but around 1500g. I know that she's still young but figured I'd see if she's ready. If not, that's ok too. My pastave girl is at the same point age and size-wise. All 3 are eating just fine though my pastave girl has started hanging out on the cool side the last week or two and looks like she's building. Still locking every chance, however. The albino hasn't shown any signs of building yet. Any ideas or just keep putting them together and see how things progress?