hi kevinfeng1978
with football, betfair has a different approach, every time there is a goal etc, they cancel all bets.
it is better to set your trigger to no more often than 90.00 sec
BUT make sure that you have the conditions
and selections back matched is equal to 0 (this is if you only place one bet per selection)
and selections back unmatched is equal to 0 (this MUST be added)
use lay in place off back for lay betting.
this will make sure that your bet stays until matched.
mcbee