CbB: "Write Enable" won't work now.

I've successfully used the "Write Enable" feature (clicking on the "W" in the track or console view) to taper down the volume at the end of a few of my pieces, and this latest one I'm working on, I went to do the same thing, but now it doesn't work.
 
I'm using CbB, if it matters -- but then I was using CbB when it did work with the other tunes. As I apply it, I get the green line with the nodes that I can go back and fine tune adjust, and when I hold my mouse cursor over the nodes, they're indicating the correct drop in dB. So everything appears to be working the same as it did (successfully) with the other tunes, but for some reason this one isn't going for it. The track is an audio track, but then so were the others. Also, in the console view, the volume slider doesn't move like it's supposed to.
 
I went ahead and saved the file as a .cwp then exited CbB and booted SPlat, then loaded the file in SPlat and played it back. No difference. The volume doesn't taper off like it's supposed to in SPlat either.
 
I've probably overlooked something simple, but I'm not spotting it. Any ideas what I've missed?
 
 

Like I said, I knew it had to be something simple. The R is usually highlighted on my tracks, so I don't typically pay attention to it. In this instance, it wasn't highlighted, and that was the entirety of the problem.
 
Thanks much for the tip, and the solution!

This one bit me too.  Easy to click the wrong button and then click the write enable and forget.