Dear Lucapac,
The invoice is generated when an order is changed to one of the statuses configured in the VirtueMart Backend. The numbering plugin does not interfere at all with when an invoice is generated. In fact, it is only called by VirtueMart when an invoice is to be created.
Regarding the naming of the invoice: The appended _20141110 appears to be a date (November 10, 2014)...
There are multiple possible causes for this phenomenon:
1. Have you ever manually removed test orders from your installation and then restarted the MySQL server? In that case it is known that MySQL will reuse the autoincrement ID, so new VM orders will get the same ID as already deleted orders. This would not be a problem per se. The other factor is that in VirtueMart deleting an order only deletes the order from the database, but NOT the corresponding invoice information from the invoice database table (since that might later be needed for the tax authorities...). So if a new order get the same ID as a previously deleted order, and that deleted order already had an invoice generated, the new order will get the invoice number of the deleted order.
2. Have you somehow reset the invoice number counter in the plugin configuration? If VirtueMart detects that an invoice with that file name already exists, it will append either a running digit or the data (the behavior changed some time in the past).
It would be helpful to know the exact configuration of our Ordernumber plugin for VirtueMart to figure out possible causes of your issue.
Best regards,
Reinhold Kainhofer
