Multi Tier Chart Forumla

Hi all,
I can make a multi tear chart if I set the category axis to cells A3:C6 however I cant if I set it to this:

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Can you please help me find a way I can type that formula so excel understands its multi tier, the reason I need to typed out is because I am creating the chart through vba.

An image of the problem is below. I want to use formula to acomplish same affect in the above:
http://img.photobucket.com/albums/v1...u20formula.png
Thanks!

Charts do not do multi level category labels when the source is a static array.