Your Blueprint looks a little bit surprising. You’re starting the line trace at a cube (makes sense), but then ending the trace at (Cube X, Cube Y, Cube Z * 10). So that isn’t going to work at all if the cube’s Z coordinate is positive, because the trace would go up instead of down. Are you sure the (negative) Z times down is far enough to reach the surface? The fact that we can’t see the shadow of the cube on the terrain in your screenshot indicates that it might be farther above the surface than it appears.