Validation

[Richard]

What am I doing wrong? Column A I've got =countif(a:a,2)=1 because I don't
want duplicate numbers entered. No matter what is entered even numbers that
aren't duplicates, I still get my warning message and won't allow me to enter
anything. Thanks in advance!!

 

[Gord Dibben]

Select column A and Format>CF>Formula is:

=COUNTIF(A:A,A1)=1

I would tend to use a more realistic range like =COUNTIF($A$1:$A$1000,A1)=1

but you know your needs.


Gord Dibben MS Excel MVP