Sometimes the boys need a little more time than people think. I've had a few males that breed great in the 700-800 gram range. typically I only pair the newbies up with proven females and just a one to one ratio with them. Experienced males see up to 3 girls here. Like Albert said, you could try to throw in the Killerbees fresh shed. You could even try to put both males in together for 10 minutes or so to get the "Competitive juices flowing" so to speak. However, if you're set on particular pairs, this may not be the best option. There is also the possibility that you're just missing it. I have an Albino "ninja" I like to call him. The first 2 seasons I bred him I never saw a single lock. Over those season I had 4 albino clutches fathered by him. Be patient, there's still time for him to figure things out. Good luck.