return a 2-dimensional array from asp.net webmethod to javascript

 I'm sending a 2-dimensional array from an asp.net AJAX webmethod to a javascript function,  but when I try to access the array from my client side function as myarray[0][0], and testing to see its content, it gives me the 'undefined' message. But when I try to send a single variable, to the webmethod to the javascript function, it runs without any problems.
am I missing something, or is there a special way to handle arrays?
thank you.
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