Please Help!!

Can I please Return a Blank when its a Blank when pulling from a seperate workbook instead of a zero in Excel 2010?

I already know that I can un click in Options, Advanced and turn off "Show a Zero in cell that have zero value." The issue with this is that It still calculates if it hides the zero. I just need the cell to create Blank and not create a hidden "Zero"

This is a real Cell Pull Example:

{='C:\Users\CntrlRm\Desktop\Treatment Plant Testing and Record Keeping\2011\9 September\[Day 1.xlsx]Daily Water Testing'!$C$21}


Thanks in Advance for your help!!