Photoshop Layers -> Flash Layers; Masking

I have been working with importing photoshop layers into Flash (both CS3) and including a layer mask created in PS.

When I load the .psd into flash the layer mask I made in photoshop comes up as a black box in flash which pretty much kills what I am trying to do.

Has anyone worked with this and found a formula to success? I am much better with Photoshop than I am with Flash so being able to use the mask I make there would be pretty helpful if I could get it to work.