OK GUYS
I think I have cracked it now. using a series of "hist_count" and "losses" and "total won" and then going to a second trigger with bm_backnum it works OK.
By the way I think I have found the ultimate "lay system". my trigger in the competition which backs horses
who have not run for 150 days or more, is by far the biggest loser i am testing.
Early indications were encouraging, however since then i have had NOTHING BUT LOSERS ON THE BACK BETS.
i hope that tomorrows test continues in the same vein, and a blank on the final day of testing will mean that we can lay these nags in the full knowledge that this time next year we will all be millionaires! I could also have the dubious privilege of by far the worse trigger tested!!