If anyone has tween-agers in the house, you know that one of the most reliable ways to leverage getting their homework done is to dangle the prospect of eating out as the carrot that gets them to crack the books.

Well, these days, to log onto their intranet homework site…

That is why I was able to extract a promised hour’s worth of reading from my 12-year-old son in exchange for a trip to the local Burger King. Not necessarily my dining establishment of choice, but the lure of ordering the chain’s Halloween Whopper was too much for him to resist.

Of courses, the book he’s currently reading is titled, “The Monster Hunter’s Handbook: How to Save Mankind from Vampires, Zombies, Hellhounds and Other Monsters,” so I didn’t exactly have to beat him with a stick to get him to plow through a couple chapters.

And for those who might not have paid much attention, the Halloween Whopper is a “seasonal” sandwich that comes with a black bun and orange tomatoes. It’s not only a brilliant marketing idea, it’s perfect for the vampire-and-werewolf crowd in the weeks before Halloween.

The chain supported the introduction with a Twitter post stating, “Something wicked is coming!” and produced a promo video clip featuring thunder, lightning, a lunar eclipse and a burger in place of the full moon. The advertising noted that A.1. steak sauce was baked into the bun, which allegedly provided the black coloring.

A black burger was originally introduced in Japan last year as the “Kuro (black) Burger,” with a black bun and black cheese colored with squid ink and bamboo charcoal, respectively. That ingredient panel would have been a tough sell here in The States, but Burger King took what was merely a novelty item and tied it perfectly to Halloween weirdness.

Here’s the problem. After grabbing all sorts of publicity for its Hallo-Whopper — it really does look impressively frightening (see photo) — management apparently forgot to pass along those Google analytics to its franchisees.

Here it is, just over a week until Halloween Day, and both the local Burger King outlets near my neighborhood not only weren’t offering the sandwich, they apparently never did.

Me (with happy kid in tow): “Hi, we’re here to try a couple of those Halloween Whoppers I saw advertised.”

Front counter person: “Uh, we don’t sell those.”

Me: “Wait — you mean you’re out of them?”

Front counter person: “No, we just don’t have them.”

Not only didn’t that really answer my question, it begs an even larger one: Why spend ad dollars on a Halloween promotion, and then decide that late October’s not a good time to market a black sandwich! C’mon, Burger King. What were you waiting for? Valentine’s Day?

Failure to launch

I grant you, in the context of a multi-billion dollar fast-food chain’s overall operations, deciding not to carry a novelty item that — at best — may only serve to cannibalize the menuboard isn’t going to make or break the business. But judging by the clueless response of the employee serving me and my son, at least one franchise owner not only failed to capitalize on the tsunami of free publicity surrounding the Halloween Whopper, the restaurant staff were never even give a plausible talking point to answer customer queries.

Talk about whiffing on a hanging curve thrown right over the plate.

True, the black Whopper checks in at 710 calories, with 43 grams of fat (54% of calories) and 1.5 grams of trans fat. But hey — this was an item being sold for a limited time only. It’s not like people are going to be wolfing down Halloween Whoppers five times a week from now on … especially if they patronize the stores where I tried to buy just two of ’em.

Dan Murphy is a food-industry journalist and commentator.