Weight Painting with X-mirror

I’m trying to use the X-mirror feature in doing some weight painting. I have it enabled, I’ve named my bones in the fashion “hand.l, hand.r”, I extruded them with X-axis-mirror enabled using shift-E. I’m wondering what I’m doing wrong.

Could it be because I initially did some weight painting before enabling X-axis-mirror and naming the bones? I erased all of that and tried to start over after renaming. Suggestions are appreciated.

John

<smacking_forehead>
I’d forgotten to apply the Mirror modifier.
</smacking_forehead>

John