Try replace your formulas on Sheet 3 with this:

Sheet3!B2=if(Sheet2!B2+Sheet1!B2=2,0,Sheet2!B2+She et1!B2)


--
renegan
------------------------------------------------------------------------
renegan's Profile: http://www.excelforum.com/member.php...o&userid=10450
View this thread: http://www.excelforum.com/showthread...hreadid=528726