I have a drupal 7 module for generating consecutive invoice numbers for übercart invoices, but there are some problems with this module. For each existing and new invoice, the module needs to generate an invoice number. For example, the first invoice gets number 1, the second invoice gets number 2 and so on. Invoices of orders that are abandonned or cancelled should not get an invoice number. The problem with the current module is that there are holes sometimes in the invoice numbers, for example the 10th invoice has invoice number 10, but the 11th invoice has number 16, while it should have number 11. I need someone who can fix this permenantly.