Linedef Executor 404 "block enemies" flag

I'm trying to set up an area with rising and falling water. I'm using Linedef Executor 404 to raise the water. From what I've read, if I set the "block enemies" flag and set the front X texture offset to the tag of another linedef executor, it will run that executor after the ceiling finishes rising. However, I can't get it to execute. I've tried pointing it at the executor's trigger linedef and at the executor linedef itself, but I haven't had any luck. Is there something I'm missing with my setup?

Edit: Never mind; I've just switched to a gargoyle box.