Conditional formatting based on value of 2 different cells

[LFinnie]

Excel 2007.
I'm trying to manage deadlines in a project plan with some visual cues using icon sets in conditional formatting.

I want my cell to display the green tick icon if the deadline date falls after today's date, the amber exclaimation mark icon when the deadline date equals todays date, and the red cross icon when the deadline date has already passed. So far so good, I can make this work by referencing a cell which displays todays date.
However, I only want my cell to do any of this if a different cell is blank.

Can this be done?

(and sorry if this has already been done to death, I've searched but can't find anything that quite covers what I'm looking for)

LF.

 

[LFinnie]

OK, I've partially answered my own question by introducing another condition first...

=NOT(ISBLANK($F$20))

...so if cell F20 is blank then my second condition with pretty icons kicks in. But this only works for cell F20 which is fine when the cell I want the condition applied to is E20, however I want it applied to my whole column, so if cell F21 is blank then the second condition would apply to cell E21 and so on.

Any clues?

 

[LFinnie]

Thought I'd just solved it there, but have now run into the issue that you cannot use relative references in conditional formatting criteria for color scales, data bars, and icon sets.
A quick trawl of the net suggests that this can't be solved

Oh well, back to the drawing board.