Masking the falling snow tut

Glad to join this forum! I like the falling snow tutorial and have used it a few times.

I’m trying to mask the snow in a snowglobe but I can’t seem to add any background layers.

The only way the mask seems to work is if all layers below the Mask layer are masked.

Otherwise, the snow generates within the boundries of the stage.

So, layer 1 is the actions, layer 2 is the Mask, layer three has the snow mc and is Masked and then the last layer is a background graphic which is set to normal. With this setup, the snow does not get masked. If I remove the last layer (which isn’t masked anyway) the mask works.

Any ideas?:q: