Burger King review: Chicken King advertising

I am watching the WCWS and seeing your ad promoting the Chicken King sandwich with an offer of a free whopper, and that is a great deal. So today at lunchtime I pull off the freeway to my nearest BK. Imagine my surprise when they tell me that offer is not available in-store but has to be ordered on the app. Well, I am driving, so no downloading the app. No Chicken King to try.
Why would you run a national ad and not honor it in-store? I guess I will stick with Wendys, Chik-Fil-A and Subway.