I am not sure what you mean by 'tracking slip'.
Was the item sold with Simple Delivery?
If you open a Simple Delivery label, but don't use it, then it will show as sent with the tracking for that label.
If you use your own label bought at the Post Office it won't show as delivered and you can't change the tracking so you will have have to wait for payment.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)