See, even I got the terminology confused and wrote the wrong thing.

COD does not mean pay on pick up.

It means cash will be paid on delivery of the item to the buyer's home.

That's not what you want. You want them coming to your place, picking up and paying you cash then.

To be honest with you though, I think a lot of buyers also get confused by the terms & I don't know that it is what is causing the problem with your sale.