Message box in ASP.Net with VB.Net

Hi,

Im using VB.Net with ASP.Net and when I click a button, i would like a message box to come up with 'Yes' and 'No' before the button does it's action.  But this produces an error.  The code is below:

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    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        'Create message box
        Dim Msg, style, title, response
        Msg = "Quit BAS Calculator?"
        style = vbYesNo
        title = "System Message"
        response = MsgBox(Msg, style, title)

        If response = vbYes Then
            'Clear all rows corresponding to the rep where e has been set to indicate that the row was edited
            Dim updateCmd As String
            updateCmd = "UPDATE KG_Forecast SET Edit = '' WHERE Rep LIKE '" & Session("UserID") & "'"
            Dim myCommand As SqlCommand
            myCommand = New SqlCommand(updateCmd, myConnection)
            Dim CurrentTextBox As System.Web.UI.WebControls.TextBox
            myCommand.Connection.Open()
            Try
                myCommand.ExecuteNonQuery()
                dgProducts.EditItemIndex = -1
            Catch exp As Exception
                lblMessage.Text = "ERROR: " & exp.Message
            End Try
            myCommand.Connection.Close()

            BindGrid("ID")
        End If
    End Sub
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Can anyone help???

Thanks in advance,

JK