Private sub worksheet_change not working

Hello
I'm having trouble with a worksheet change code. No problem with this type of code elsewhere in the workbook but on this particular sheet it is not playing ball.

Code as follows:

Private Sub Worksheet_Change(ByVal Target As Excel.Range)
    
    If Target.Address = "$c$4" Then
    
    Call Auth
   
    End If
     
End Sub

Nothing happens if I change cell C4. If I disable that line then the Auth macro is called if I change any cell (including c4 which is a drop-down list) in the offending worksheet. Have run

Application.EnableEvents = True

in a separate macro but still no joy.

Any help, as always, much appreciated