It has an object doesn't support this property and I don't see anything wrong.

Sub AddNodeCommas()
Dim SlashPos As Long
Dim myCell As Range

For Each myCell In ActiveSheet.Ranges("D2:D122").Cells
If myCell.Value = "" Then
'skip it
Else
SlashPos = InStr(1, myCell.Value, "/", vbTextCompare)
If SlashPos 0 Then
'/was found, so skip it
Else
myCell.Value = myCell.Value & ","
End If
End If
Next myCell

End Sub

tia,