If a male is producing sperm plugs, it means he's capable of breeding, but that doesn't mean that he definitely will breed. Our first Yellowbelly male would not breed until he was four years old and about 1500g, even though he was producing sperm plugs. On the other hand, the Pied het Albino that sired my double het Pied Albino males (they are proven now) bred and sired 3 or 4 clutches at 290g. Not that I'm advocating breeding such a small male...and I didn't, the guy I got them from did, but I'm just saying, it is possible.