I think it may well be down to light, Anne.
We have six different peppers growing in our GH, and just today, I chucked the toms, which were darkening the peps, and some are only just flowering - Thai Dragon (hot beast apparently)...
Some are away and producing, like Cayenne, and a capsicum type, but the light was reduced by just a few bare-looking toms, so they're picked and back in the house, and the plants happily composting!