Can't use join command on wall on top of another?

[Anonymous238]

Trying to remove the line between these 2 walls which are of different depth. I tried using the join tool but it won't let me select the other wall. How should I remove the line?

[barthbradley · Accepted solution]

Are they Joined now (e.g. via Join Geometry)? If so, press the Align Command in that 3D View and then select both walls.  That fix?   

[Anonymous238]

Had to unjoin and then rejoin walls