You may find that you have a missing invoice number in your list when viewing a sales report, for example. This means that a user has deleted the invoice. Commusoft will not re-use an invoice number so it will skip this and continue on with the sequence.
If you have created an invoice in error, the best way to deal with this is to create a credit note against the invoice. This will keep an accurate history against the account:
Add a credit note against an invoice
If you'd like to find out who has deleted the invoice, this is available on our enterprise price plan and details of this can be found on our website: www.commusoft.co.uk/pricing.