Which of the many solutions on those two web pages are you talking about?

If the one at http://cpearson.com/excel/NoDupEntry.htm, did you use
absolute references for your input range?

E.g.,

=COUNTIF($A$1:$A$50,A1)=1

not

=COUNTIF(A1:A50,A1)=1

????

Select column A, inputIn article
,
"Courtneyf04" wrote:

This solution does not allow me to check for existing numbers. Lets say that
I have a list of numbers but change a number somewhere near the top. Data
Validation does not check that number.