On Jul 16, 4:01*pm, DRKENNE wrote:
I'd like to conditionally format a column (add color) based on the date value
in W1 and where cells in the column G are null.

Maybe an example, with more information? Where is it caluclating the
null or zero from?
Try this.

Cell W1 = 07/20/09
Formula in G1 is =IF(H1="","",$W$1-H1)
Conditional formating in G1 is "Cell Value is" - "equal to" - "0"
Format your color in the format section
Select G1 and fill down column G your desired area.
Place a date in Column H to generate a number in G