Masking a movie clip

Is there some trick to masking a movie clip? I have two movie clips that I am placing on the same layer and duplicating about 20 times. One is a ball that vibrates and I can mask that one with no problem. The other movie clip is a ball that bounces around the screen. No matter where I place it, this bouncing ball will not get masked.

I have no clue what is going on. Help would be much appreciated!

JRW

um, drag the bouncing ball under the mask, so that it is indented a bit

that way it will be part of the same mask that the top one is.

You might try using setMask(). Give it a look up in the AS Dictionary.