I bought 2 new triggers in case it was faulty and still the same. The flash fires off and even if it didn't, I would have thought (at 60th F8) I would have got something from normal lighting but out of 12 shots maybe 3 or 4 will be black.
I have a neewer flash trigger firing off two external flashes. Camera is set on manual, 60th second at f8
Some of the shots come out black while others are fine ( not just a black band but completely black)
I bought another trigger in case that was at fault but made no difference.