Match back bets 3rd best price

Hello, coming back to this subject regarding matching back unmatched bets I am still having trouble with this.
I am trying different stakes and testing them at higher odds in the hope the trigger matches those unmatched bets at the current market price but to no avail.
I am still getting the error:
There is an error with an action that caused the entire order to be rejected. Sometimes the error includes There is no potential loss on selection xxx

The trigger works in test mode but not in live mode.

Hi
From what you have posted so far I think most of the problems you are having are because of small bets. Earlier Tim mentioned about lay bets, but some small back bets can be rejected by Betfair as well due to the "unfair rounding" loophole Betfair wanted to close.  They quote this back bet as an example which would be rejected:

For example – a 13p @ 1.06 back bet is ‘unfair’ as it ‘ought’ to win 0.78p, but actually - due to rounding - wins 1p, a 28% uplift.

much is written about this on the forum and on Betfair
you mention you are back dutching which could complicate things as the back amounts are variable.
MFP has a method of placing bets below the minimum, but this has a massive time lag due to the process involved, and trying to match a below minimum unmatched back bet in-play is very likely run into some problems with bet rejections.
The only thing I can suggest here is to ensure every back bet is £1 or higher.
If it helps, there is a formula here which will disallow a dutch if any amount is below a quoted minimum.

The "no potential loss" error is generated by the Spread Loss trigger action when the trigger fires on a selection whose P/L is not negative.