How to prevent API from generating duplicate lines or invoices

Hi Everyone

 

I have written and application that acts like a translator between InfinityPOS and MYOB AccountRight.

It has been working for years and I have several clients using it.

Lately some customers have complained about having duplicate invoices imported and also sometimes an additional line in the invoice.

This interface imports Customer and Supplier Invoices and GL Journals and wanted to check with the community if there is anything I can do to fix it.

It only happens 2 - 3 times a month at random and it can be any type of transaction.  Sometimes it might be a extra line in an invoice sometimes an extra GL Journal.

The system does check if invoices and lines are travelling OK and will not flag an invoice for example as being transferred if it does not get success codes along the way.  I could build a delay loop in but I do not want to slow it down as it already takes a while to do everything during a daily transfer. 

My question is :

1). Does any one have issues with this type of problem ?

2). If you do have issues have you fixed them up or can anyone provide any ideas on how they could be fixed up.

 

Thanks in advance

David