Date format changed to text format

Folks,
I would like to use the function offered to me below. In cell C2 I enter my date as text, 11/27/2013, In cells A3:A16 I have dates also formatted as text, same as in C2. Cell D3 holds the product number also formatted as text. The same formatting also applies to B3:B16, text.

{=SUMPRODUCT((DATEVALUE(D2)=$A$3:$A$16)*(D3=$B$3:$B$16))}

The result is #VALUE error.