Masking multiple clips with setMask and duplicateMC

Hi guys. Since setMask can’t be used to mask multiple clips (as you can do easily with masking layers), I figured I’d just duplicate the original mask and do an additional setMask. So I thought:

text_mask_mc.duplicateMovieClip(text_mask2_mc, text_mask_mc.getDepth());
shine_mc.setMask(text_mask_mc);
solid_mc.setMask(text_mask2_mc);

But that does nothing, the maskees just sit there and so does the original mask-to-be.

Maybe I’m just sleepy, but I’m missing something. Thanks for your help!