Generally if the sale doesn't appear on your event sales list it is because the transaction was not successful or didn't occur. Did the ticket purchaser record the transaction number? (this is displayed after a successful transaction).
Alternatively, if the ticket purchaser can check their credit card statement and provide you with:
· The date of the transaction
· The amount of the transaction
· The first 6 and last 3 digits of the credit card used to make the transaction
You can forward these details to firstname.lastname@example.org and we will look into it further.