Data validation: If previous column is having a value, then return FALSE else TRUE

Now, the file is attached.

Sorry for the inconvenience.

acsishere.

Is it not possible? Any other alternatives?

acsishere.

Thanks for your valuable time. If you say that it is not possible with formula, then I will try to change logical design of my worksheet.

Thanks a lot for your guidance.

acsishere.

Here is a possible solution using the data validation in combination with VBA. The VBA code is connected to the spreadsheet (Right click on Sheet2 tab and "View code"). What it basically does is erases your entry if there is an "S" in column 6 (F). If not, your data validation works normally.

The code is as follows

Private Sub worksheet_Change(ByVal Target As Range)

    If Target.Count = 1 And Target.Column = 7 Then
        Application.EnableEvents = False
        i = Target.Row
        If Cells(i, 6).Value = "S" Then
            Cells(i, 7).Value = ""
        End If
    End If
    Application.EnableEvents = True
    
End Sub

ChemistB

Thanks a lot for your code. It works very nicely.

Again, Thanks! Thanks! Thanks!

acsishere.