Hi YUKI_ARISA,
I really don't know if this will work but open your duplicate options box and make sure "Duplicate Input Connections" is selected. I have Maya 8.5 and so it's in my Duplicate Special Option box. I just remember reading something about that and figured it might be worth a try. If it doesn't work, I'm sure someone more knowledgeable will come along and post the answer.
edit: by the way, welcome to SimplyMaya!
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