Still haven't gotten it to work - are you placing the wall item from your inventory, and staying in the wall item list to place it? When I do this and use the subcommands key, I just get options to turn on grid and counter.

If I switch categories to all, I can get a Place command off the non-wall item, but it gives me an error and won't let me actually place it, even when I spam it everywhere possible on the wall.