Repeatition of the same item

I want to avoid repeatition of the tags in the rows i am entering. ie.. if i
have entered 98TI-107 once it should notify me if i am trying to enter it
once again.
Thanks

Data>Validation>Customized
Formula: =COUNTIF(A:A,A1)=1

HTH
--
AP

"S.G.Pillai" <SGPillai@discussions.microsoft.com> a écrit dans le message de
news: 997D01E7-86F3-4D34-9DD2-D70BE9ABBCEA@microsoft.com...
>I want to avoid repeatition of the tags in the rows i am entering. ie.. if
>i
> have entered 98TI-107 once it should notify me if i am trying to enter it
> once again.
> Thanks
>