Hello and an advance "Thank you!" to anyone who can help.

I need a formula that will tell me if I have an upcoming demand for a
product (90 days from today's date), but no PO to match.

Example: Today is 2/16/05 - Cell a6 contains my product due date of
5/16/05. Cell b6 is empty (should be PO #).

My current formula only tells me the date the PO should be in my hands
(Sheet1!A$1 references today's date).

=IF('2005 Forecast'!A6Sheet1!A$1,+'2005 Forecast'!A6-90," ")

How do I modify the above formula to include the cell that should contain
the PO # and only give results if that cell (B6) is blank?

Perhaps I shouldn't be using the IF function?

Thanks again - Sue