Matt,
To use the actual palm shape, you have to follow the instructions in the first post exactly, and forget about DoubleClicking anything anywhere:
1) Select the top part along with the A and make it black as in the first image;
2) In the Transparency palette flyout click Make Opacity mask with both Clip and Invert Mask unticked.
The DoubleClicking is useless in your case. It can be used for another purpose, namely if you wish to create the path, not appearance, to be used as the masking shape.
