Matched Bets In SP Markets

Hi

Just a quick query and something that is causing me issues with my dutching strategy. 
I lay in SP markets only shortly before the off and I have found, particularly in greyhound markets, that despite having unmatched bets with the feature Match at SP - there is at least one or two events each day where one or two bets will be matched but then at suspension the remainder of unmatched bets are still showing as unmatched - after a period of time the bets are then deleted or disappear and leaving me with big exposure on the couple of matched bets. 

I only have only sp markets selected in locater and my trigger conditions. I am laying between 20-40 liability per selection but can dutch 3-5 selections a market or even more and if some of them don't get matched I'm in trouble. Any ideas as to why this is happening or can I include a failsafe in my coding? Any help will be much appreciated. 

Hi
I have a feeling this has to do with unmatched lay bets not meeting Betfair's minimum liability for SP lays and then being cancelled at the off. This Betfair help page explains it, and I think what you describe happening is detailed in the last paragraph.

If you think this may be the case, rather than Take SP could you match unmatched bets at best current price just before the off? 

Hi Mark.

Thanks for your prompt response. As always. 
 
I read your article and this not applicable to my situation. This article talks about partially matched bets and the unmatched amounts being below the minimum required £10 liability. For e.g. Monmore (Greyhounds) this evening took two bets at £ 20 liability each but cancelled the two separate bets on differing selections which also had 20 liability. Could it have something to to do with unmatched amounts on the selection, betting order, market volume? 99% of the markets are ok and get matched at "match at sp" but it only take a couple to behave like this to negate any daily profits. Your suggestion is all good but I find in lower liquid markets my profit is negated by the difference in back and lay prices. 

Hi
Trying to narrow it down. Perhaps check the program log for withdrawn runners.
I had a quick look at Monmore results:
16:18 5 ran 1 named non-runner
17:18 5 ran
all other races 6 ran

From Rules and Regs:

Greyhound racing
13.1 General
All bets (excluding those struck on ante-post and Australian licensed markets) are placed on trap numbers. Greyhound names are displayed for information purposes only.
Markets will be determined according to the official result at the time the track gives the result green light status, either in the form of an announcement or by display. Subsequent disqualifications, appeals or amendments to the result will be disregarded.
If a non-runner or reserve runner is declared, then all bets prior to the update of the market on Betfair will be void and all unmatched bets including ‘Take SP’ and ‘keep’ bets will be cancelled (except for certain SP bets as set out in Paragraph 10.5 of Part B above).
If there are no finishers in any race or any race is declared void before the official result is declared then all bets will be void.
If the scheduled venue is changed after the market has been loaded by Betfair, all bets will be void.
In ante-post markets, all bets on individual greyhounds stand whether the greyhound runs or not. All ante-post bets will be void if the competition is abandoned or the venue is change

From SP Rules and Regs:

10.5 Specific conditions for SP bets for non-runners in greyhound racing markets
ALL SP bets will stand so long as your trap selection is not vacant or after your bet placement a reserve runner is not subsequently entered to run from your trap selection.
ALL unmatched ‘Convert to SP’ bets will be cancelled when a reserve is added or a vacant trap removed.