Can't make credit invoice


I am trying to make an credit invoice and im getting an error stating that there is a PHP error because of credit_invoice.php the same as:'Undefined variable credit_invoice_group' on creating credit invoice

Only problem right now is that I’ve selected a invoice group and that the ID (number) of the invoicegroup is counting up, suggesting that the invoice actually belongs to a group.

Do you got a solution?

What exactly is the id of your current invoice and what template do you use for the invoice group?