A* Pathfinding project error

Hello,

I am currently attempting to implement A* pathfinding project into my unity project. But I am getting a red grid when I run the scan. I am wondering if anyone else has seen this?

First I created a plane and named it ground. Secondly I added it to a new layer called ground (I am not going to try obstacles yet).
Then I run scan and it is all red.

 

ya me too hapend to me when I added a video player in my game it said the same error