It's half way through a betting afternoon here, and I can report the following.
My computers (2 of them) do not seem to acknowledge any variables beginning with "bm" unless the race in question is the active screen, and then only intermittently. It has me completely baffled why this should be.
Whenever it does recognise the variable, once the result of the race is downloaded from the results service, the bm_backp variable immediately goes to zero, and therefore is not carrying forward to the next bet, so that the variable p remains always at 1.
As you have said the trigger works ok on your computer, could it be something in my set up. Is there anything I need to reconsider?
I have not changed your trigger except I am betting at 0.10 mins before the start, and I have added some volume, market %,and runner number conditions.
My apologies for this.
Regards,
bobh