Trip Planner Issue

I open Garmin Basecamp, navigate the menu to Trip Planner > New Trip and the dialogue box pops up: "Detailed Map Needed - The trip planner feature is not compatible with the current map. Please either connect your Garmin device to use its map or select another map to use with trip planner." (And below it reads: "Purchase map online.")

Well, I'm hooked up, powered up and updated my Garmin RV770,  my Garmin Express - so the software and maps seem to be up to date.  So just to be sure, I clicked the "Purchase map online" link to see what would happen and it took me to Maps and Map Updates. I clicked "Automotive" (as my device category) and the only thing that is an option is "Download Garmin Express" which I already updated!

So, I download it again just to make absolutely sure and install it again: "Garmin Express is already installed."

I believe I've gone full-circle.  Is it that Basecamp is just not compatible with the RV770? Because I cannot think of anything I may have left out.

Thank you in advance for any help you might provide!

Gardner