Identifying cancelled bets

[khughes]

One of the functions my app has to perform is to identify if an order, that it has placed, has been cancelled externally. By externally I mean by another app or manually via the website. It currently does this by examining the list of orders returned for a specific market by listMarketBook. If an unmatched (or part matched order) is missing from the list and the market is still OPEN then it assumes that the order has been cancelled externally. This seems to work fine, most of the time. I had an incident today, however, where an order that the app had placed was flagged as cancelled in this way but I know it definitely had not been cancelled (and it was not matched).

So my question is, was this an error in the API (removing the bet from the orders list prematurely) or is my method flawed? If it is the latter then what is the best method for identifying externally cancelled orders?

Thanks for any help on this
Kevin