Simple MSGBOX code correction

Dear Friends,
I have a simple MSGBOX code requirement. In this if the range (No_Data_Range) has a value “add” then user should get the message “ Sorry No Data Allowed”.

Sub test()
Dim No_Data_Range As Range
If No_Data_Range.Value = Add Then
MsgBox "Sorry No Data Allowed"
End If


End Sub

I am getting error object variable or with block variable no set. Also this message should be displayed automatically as "Add" value is displayed in range.

Thanks,
Nisha