Can't Add new Attachment on Sales Order attachement tab

Dear Experts,

We run SAP Business One 9.1 PL10 and SQL 2012.

When our customer want to add a new attachment on sales Order tab "Attachments" he receives the following error message:

"another user or another operation modified data to continue open the window again order (ORDR) (ODBC-2039)"

Please advise if you have faced any scenario like that.

With Best regards,

Christos Ladis

https://www.google.gr/search?espv=2&biw=1366&bih=623&q=another+user+or+another+operation+modified+data+to+continue+open+the+window+again+order&spell=1&sa=X&ved=0ahUKEwiJ4c2qv8jNAhXHK8AKHZqlBdIQvwUIHCgA