Im new to after effects and i am using CS4.
Anyway, i have made this video on there and i am trying to mask this tree out of the video because i need something to go behind it. So i had created a new solid, turned the eye of so icouldnt see it. I then drew around the tree with the pen tool (with the solid selected and rotobezier unchecked). But here is the problem, once i finished drawing around the tree and connected the lines, the area around the tree has not gone black? Why? I need something to go behind this tree! What am i doing wrong??? thnks
So you have the tree layer, intact; and a new solid layer on top of it masked by the pen tool to the shape you want?
To the right of your layer name in your comp is "TrkMat". if you don't see this, press the "toggle switches/modes" button at the bottom of the timeline window. By default it's set to 'none'. Drop it down and try "Alpha Matte <name of your solid>". If the cutout solid layer is over your tree image, this should work. If the mask looks backwards, do the "Alpha Inverted Matte <name of your solid>". That should use the transparency (that you drew with the pen tool) from the upper layer, and apply it to the layer below.
Not sure what else is going on and/or if there is a reason you didn't just mask out the actual layer you wanted to, instead of messing with a separate solid layer. But that's a discussion for another day and hopefully this will work for you.
Hope that helps!