Raycast ignore layers except

I am trying to make it so that, if a player clicks a valid place on the game-world, a selected character will move there. So I am raycasting and grabbing the location where it hits as a target destination.

However, I have had problems with the raycast hitting other things like scenery, and other characters, rather than ignoring them until the ray hits the ground (which is the location that I want).

I tried this: float range = 50; Ray raycast = camerad.ScreenPointToRay(Input.mousePosition); RaycastHit hit;

     if (Physics.Raycast(raycast, out hit, 8)) {
         if(Input.GetMouseButtonDown(0)) {
             selectedPosition.transform.position = hit.point;
         }
     }

... and then put the map tiles into Layer: User Layer 8 - "Walkable"

However, now all clicks are ignored. What am I doing wrong? Thanks!