Error on data validation cells

[markgrace]

Hi

I receive the following error when I try to put a validation on a cell.

Links_are_not_working__but_displays_information_correctly

I created the validation criteria as a list box, which was a range of 3 cells.

All was working fine until I copied data from an external spreadsheet (which had the same values in these cells as the drop down list had), I noticed the drop down list has disappeared in the cells and when I try to put the list validation back on I get the above message appearring in the Name box (left end of the formula bar)

Does anyone know how I get rid of this message and re-link my drop down list??

Thanks in advance

Sorry forgot to add using Vista Op system running office 2007, thanks