I'm moving this to "Triggered Betting".
May I suggest adding this condition to your trigger:
At Least One Selection's Saddle Cloth Number is equal to [number]
If there are no active selections with the given saddle cloth number, this condition will return false.
It'll also return false if the number of runners is less than your number. In that case you may add this block of conditions:
AND
At Least One Selection's Saddle Cloth Number is equal to [number]
or Market's Number of Selections is less than [number]