I created and sent an invoice over a month ago, and now when I'm reviewing it for payment, I see that the amount from one of the slips is different from the amount on the PDF that was emailed to the client.

How could this happen? I think the invoice was redone before being sent, so am I seeing the older copy? I always make sure to "save a copy" when I create invoices, so I expect it should have replaced whatever might have been there...

I would like to avoid this problem again, so I'm trying to understand how this discrepancy might have happened--has anyone had this problem?

PS, since Billings philosophy is that invoices are supposed to be immutable, and we have to hack around to adjust them (delete-renumber-redo-renumber), this experience shows again that the current method isn't working: it just creates too much room for errors.

Just a note that I had this happen again on another job... my invoice PDF file shows almost $200 more than my record in Billings...

I don't know what I'm doing to cause this, but it certainly isn't anything overtly stupid... Obviously Billings didn't replace the generated file when I redid the invoice, so the previous one got mailed out.

Now, to correct this is a huge hassle. Again, we aren't allowed to edit the invoice: according to the developers, this is a "good experience".

Now that I think of it further, I wonder if this is what might be happening:

When you attach a file to an email and you have the message window open, the attachment file can't be replaced: I've seen this independently of Billings when exporting a revision to a proof for example and trying to replace the existing PDF file. You normally get an error that the attached file is "in use".

So, I wonder if Billings doesn't replace the invoice PDF file if an email message with that file is open?

Haven't tested, but these would be the steps to reproduce:

• Generate an invoice with the "send an email" box checked.
  
• Leave the message window open, realize that you need to make a revision to the invoice.
  
• Return to Billings and delete the invoice, putting the slips back under "working".
  
• Open Preferences and set the invoice number back by -1.
  
• Add a forgotten slip, or revise an amount.
  
• Select the slips again and generate a new invoice which should have the same number.
  
• Close the email message window with the old invoice.
  

After these steps, I suspect we would see different amounts on the email, when compared to Billings...

If Billings can't replace the invoice file, it should generate a visible error! I suspect that it's failing silently, and I'm left with the new invoice record in the program, and the old one gets sent out.

Can anyone confirm if this is what's happening? I'll test it myself when I have more time.