Hi slippy,
Which country are you located in?
I found a couple of old messages in the forum that reported the same error. Both appeared to be because of the country being banned or restricted.
topic962.htmltopic1220.htmlAccording to the Betfair API documentation, the error code 'ERROR_IN_ORDER' means that there is a problem with the parent order (i.e. the submission containing your orders). So if it is not a country restriction, then there must be something else wrong with the submission. If so, we might need to look deeper into the bet(s) you are trying to submit to look for other reasons that they might have been rejected, so I'd probably need to know whether you sent the bet from Excel, the ladder or the grid and whether it was a batch of orders or just one? Also what was the odds and stake?
Kind regards,
Gavin