Hi STONE
Thank you for your post, I have some troubleshooting which should help. Can you check the history of this customer if there are any other credit notes by doing the following:
1. Open find transactions
2. Select the card tab
3. In the search box type in the customers name
4. All of the credit notes will show in a list (you might need to move the dated from back)
5. See if you can find a transaction with $0.00 or it might have the word "VOID" in the amount column
6. Delete/reverse/edit that transaction so its no longer showing an amount of nothing
7. Try again to Delete or reverse the credit note you were attempting to delete when you got the error
Let me know how you get on and if you require further assistance, happy to help.
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