Symmetry with hand pose doesn't seem to ever work

I have a problem with copying/mirroring hand poses... whenever I pose a hand and then try the Symmetery option (Shift-Y), nothing happens...
I've never figured out how to mirror hand poses. What am I missing here? It's annoying to have to pose each hand individually, when you're going for the same pose.
Comments
Are you using Pose Controls, on the hand or on the figure, to pose instead of the individual bend/twist/side-to-side controls on finger bones? If so you first need to use the bake to Transforms command to turn them into bone settings.
I hazard the guess that you're using pose controls ("fingers grasp" and the like) for at least the rough initial posing, rather than visiting each finger joint and using the primitive bend/side-to-side/etc. Most of us do I suspect because hands are such a tedious pain in the neck to pose joint by joint from scratch.
Pose controls that consolidate multiple actions and targets in a single dial tend not to play well with automatic symmetry. To get predictable results I have to "bake to transforms" (under Edit/Figure I *think*, I'm not in a place where I can check.) Then when you run the symmetry pane you'll probably want to permit mirroring across both X and Z axes.
Never mind, didn't get an answer.