The ad makes the promise.
The shelf has to prove it.
An advertised price can earn the trip.
But when the customer reaches the shelf, the ad stops doing the work.
Now the promise belongs to the store.
The item has to be there. The price has to be visible. And once the sale starts moving, somebody has to keep watching what the customer is telling them.
There are two versions of the same failure.
The shelf is empty.
Or the product is sitting right there without a price the customer can confidently connect to the offer.
Either way, the promotion disappears at the exact point where it was supposed to become real.
That's why advertised items cannot become background noise once the ad breaks.
If an item is outrunning the plan, refill earlier.
If it isn't moving, check the price, the position, the sign, and the presentation before assuming the customer simply isn't interested.
A great price can get the customer through the door.
Execution is what makes the offer believable.