Cannot Align Semi-Transparent Items?

Windows Vista, Photoshop CS2.

Steps to repeat:

1. Create new document
2. Fill a circle on a new layer
3. Drop opacity of filled circle to 10%
4. Create new empty layer below circle layer
5. Merge empty layer with filled circle layer
6. Select entire canvas
7. Attempt to align layers to selection
   layer > align layers to selection > vertical centers

I get the following error:

Could not complete the Vertical Centers command because there are no layers to be moved.

Clearly this is not true, as I'm selecting the layer with the semi-translucent ball on it. Now, if you had tried this same command prior to step 5 (when the layer was at 10% opacity) it would have worked.

Is there some way around this problem? I need to move layers around that begin as transparent items, with a layer opacity at 100% where 100% of the layers opacity results in showing objects that are themselves not-very opaque.

I've confirmed on another machine that this problem doesn't exist in CS3. I may exist in earlier copies of Photoshop, but I only have access to CS2 (has the problem) and CS3 (does not have the problem).