Note that IFERROR was introduced in XL07.

In article ,
Rod wrote:

if you only need to find the missing data, and don't need to
validate correct data you can use
=IFERROR(VLOOKUP(A1,'Sheet 2'!$A$1:$A$100,1,FALSE)),"Missing")
and this will work just for finding errors in your range without having to
validate any other data.