I have a worksheet that has all of my inventory part numbers in column A. I
am using a lookup function requesting that on worksheet 2 it lookup the
partnumber and return the number of units sold in Jan 2007. If the part
number is not on the Jan 2007 page the formula is picking up a number anyway
rather than returning a 0. I'm not really sure why or where it's getting the
number from.

My formula is: =LOOKUP(A103,'2007 January'!A:A,'2007 January'!G:G). Thanks
in advance for your help.