Doh! I had been using E1 instead of E2 but pasted your formula...

Building on your example, I used the list instead of custom for validation
and Custom formatting to highlight when I had a duplicate entered.

Thanks again!

"Bernie Deitrick" wrote:

The formula will prevent entering the same value twice.... the "COUNTIF($E2:$E$25,E2)=1" part does
that - try it....

HTH,
Bernie
MS Excel MVP


Thanks Bernie!

That helps prevent me from entering an invalid position and that is helpful.
But I what I really want to prevent is entering the same position more than
once.