Hi, pls what's wrong with the code below?

(PLS NOTE: optNumber is a radio button array, txtNumber is a text box)


Private Sub optNumber_Click(Index As Integer)
Dim OldNumber As String
Dim NewNumber As String

OldNumber = txtNumber.Text

NewBase = optNumber(Index).Tag 'problematic line

I keep getting the following error:

"run-time error 13 - type mismatch"

I'll be very grateful for any assistance offered