Using Excel 2010
Is there a way to convert or add an “If” function to the following formula? I use this formula to add the delivery date by vendor on my report (located on sheet2). However, if a date is not entered into column F for a certain vendor then 1/1/00 appears on the report (located on sheet2). I would like for the cell to be left blank if no date is entered in column F.
Any help is appreciated.

=SUMPRODUCT(('Sheet1'!$A$2:$A$5000=A8)*('Sheet1'!$B$2:$B$5000="Delivery"), 'Sheet1'!$F$2:$F$5000)