Photoshop :: Masked Out Elements Still Selectable With Magic Wand Tool?

When I want to cut an item out of an image, I create a mask on the image's layer and paint out everything except the item I want to keep. Something has changed and I can no longer select that remaining item in the layer after I've applied the layer mask and essentially painted out everything else.
 
For instance if I wanted an apple cut out of a tree, I would paint everything in black except that apple, which remains white in the mask. After applying the mask to the layer, I should be able to click in the empty space around the apple wtih my magic wand tool and have it make a perfect selection around that apple, yet the magic wand tool is still picking up the leaves, branches, etc. Even though I've painted them out and applied the mask, essentially deleting them, and all I can see is the grey and white checkerboard grid behind the apple.

This is Photoshop CS6 and it was working fine before. Did I change something without realizing it?