ive had terrible times germing, had some just pop out ready to go, then 2 batches in a row never came up i was pissed so i wasnt taking no chances when I got the Subcool jack the ripper seeds
followed his advice i got rapid rooters soaked them with distilled water from the pharmacy and they came up like daisies
I think your problem may lie with the heating mat
i think its better without one. just have some lights hi above them keeping them warm
also to test this theory here is the question:
were the seeds that sprouted in tottaly random spots or did they sprout in an area that might of had less heat on it from the heating mat?
also did you use distilled water?
also maybe it was too cold or somthing like that when your batch shipped causing them to spoil?
did the ones that sprout all come from the same strain or were the sprouted seeds all random as far as strain?