I'm gonna be Debbie Downer here, but I think you have to consider this a 'failed transaction'.
I assume that your other 60 transactions used PP as payment processor with no problems?
Either you have him Blocked (along with hundreds of other deadbeats) for having two or more Strikes for non-payment, or he is in a location that you do not ship to.
You have opened the Unpaid Item Dispute.
The buyer has about five days to pay up. If he doesn't, do NOT cancel the dispute, end it as still unpaid.
Cancelling is used when the transaction has been smooth but won't be completed. Both parties can leave feedback. This is not that case.
Close the Dispute as soon as you can - try to do it every day if you have time- and get your FVF back before the next billing period is up.
He gets a Strike and cannot leave feedback.