Hi,
Thanks for your reply.
After getting the error message, I searched SCN, and noticed an entry about reconciling, which I thought I'd try out, just in case.
After reconciling the BP, I went back to the open invoices widow, and it still showed up as 'open', which is when I created this query.
However, I have since closed SAP whilst I left my desk. I reopened after reading your reply, and the invoice is now closed, so my problem is resolved.
Thanks for your speedy response, very much appreciated