Customer Not Found Import Error

We are trying to import item sales into our MYOB file.  Even though we have told the import to match on card number, past experience has shown that the customer name in the software that is creating the import file has to EXACTLY match what is entered in MYOB or the transaction will reject with a 190 error, customer not found.

We have a new customer and last week when we tried to import item sales we got a customer not found error. Since it was a one line sale, we manually raised this entry and I copied and pasted the customer name from MYOB to the external source so that I could be sure they were the same for future imports (as this is a weekly process).  We verified that the customer number is the same in both systems.

We got the error again this morning trying to import, for the same customer.  As an experiment I tried deleting spaces from the name in the import file and in the MYOB card file, and re-ran the import. This did not fix the issue.  There is another customer that has a very similar name but I cannot see why this would be a problem as we have multiple customers that have very similar business names (all starting with the same word) and they import with no problem.

I am lost as to what could be causing this issue or how to fix it.  It has been fortunate so far that they have only been invoices with minimal transactions and it was viable to manually enter, but as the customer is new and their usage increases this will not always be the case.  We had roughtly 100 invoices for other customers that all imported with no problems.