Brush-face will not convert to displacement

As the title says, I cannot make a brush-face a displacement. I go through the proper channels, leaving it at 3, I hit O.k. and nothing happens. And it’s just the one brush-face, I’ve done all of the others. I’ve tried restarting Hammer, remaking the brush, you name it I’ve done it. The solution still eludes me. :sigh:

Its not a quad.

I’ll try that. Thanks.

Edit:

I feel sheepish… That was exactly the problem…

(Your avatar fits perfectly…)