Data Validation only works if you enter something into the cell concerned
and hit Enter, this is documented in Help. Copying or cutting a value into
the cell will not trigger the validation and also dragging a value from an
adjacent cell will not trigger it either.
It may be possible to do this using code but I'm not sure. Try posting to
Excel Pogramming , there are a lot of very well informed people on there,
Regards,
Alan.
"jk" wrote in message
...
Hello,

The data validation response i received on my intial posting worked when
you
manually key in the same value preventing duplication but when i tried to
copy and paste the same value it ignored data validation and allowed a
duplicate entry. I need something that will worked weather manually keying
or
copy and paste to prevent duplicates. Does this require VB or macro use?

Thanks



jk" wrote:
I need something that would highlight the cell entry if there is a
duplicate
entry located on the sheet.For instance, i enter account N15650 in the
account column and if this entry has previosly been made in the same
column
then i want this new entry to be highlighted as a flag for me.Does this
require a macro or vb for this action?

Perhaps try also Data Validation ..

Assuming it's for inputs into col A ..

Select col A
Click Data Validation
Allow: Custom
Formula: =COUNTIF(A:A,A1)<2
Click OK