Don't eat me, please help me. You have to understand that this masking stuff is going to doom my AMV to be unless I get it to work.
I need to mask out the background of a certain scene so that only the character is "visible." Simple, huh? He will be placed against a new background, eventually. I slapped a mask on him in AE, but it took forever using that dratted pen tool, so I figured I'd export the frame to PS, create a mask a la alpha channel goodness, and import it back into AE.
Maybe this is where I'm going wrong. Maybe I can't do this at all (the alpha channel masking in PS for use in AE). Maybe I need to export every frame to PS, cut out what I don't want, and import it. But this just doesn't seem logical. If I've got to mask out the background of a static character whose eyes/mouth is moving, this just won't work and this is what masks are designed to handle.
The problem is that I cannot create an alpha channel mask in PS. I cannot get my alpha channels to stick. No, not even stick, apply themselves! What's worse, it used to work for me. Once upon a time, using E-ko's method, I actually created an alpha channel mask that worked like it was supposed to in Premier. Now, suddenly, for no apparent reason,
It. Does. Not. Work. For. Me. I've referred to other, quite similar methods for mask creation, and THEY do not work for me.
I think something's bonkers with my PS program. Up until the point at which I hit "apply layer mask" everything looks decent (alpha channel exists, with correct transparency). However, applying the mask to my target layer deletes the entire contents of that layer, and of course takes my carefully constructed alpha channel mask with it! PS never did this to me before...
Maybe my ideas about alpha channel masks are messed up...maybe that's the problem.

Maybe what I thought I did when it *worked* was something else completely? I have no idea. But I'd love to figure out what's wrong.
p.s. I can cheat a little using alternative blending modes in Premiere/AE for B&W images used as masks, but it's not ideal. I also can cheat a bit using track mattes, but again, it's not ideal. Alpha masks are such a simple thing to create, and yet I can't seem to do it. Any advice (including reinstalling my PS program, which is what will happen if it doesn't start cooperating) is much appreciated!