Thanks, arnie! Yeah, I'm aware of that limiting factor--they won't even go indoors if they're "too hungry to think about that!" LOL But, they're breeding now--so I don't know what it was. Maybe I just didn't try enough times. Maybe I caught them all in the wrong part of their cycle.

Maybe they ate something that limited their fertility? Dunno. But it seems to be fixed now.

Thanks for all the help!