Databinding error

Code:

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Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        Dim al As ArrayList = CType(Session("AnswerList"), ArrayList)

        resultGrid.DataSource = al
        resultGrid.DataBind()

        'Save the results into the database
        Dim answers As Answer = New Answer()

        Dim questions As Integer

        questions = al.Count
        al.Add(answers)
        Dim correct As Double = 0

        Dim i As Integer = 0
        For i = 0 To al.Count
            Dim a As Answer = CType(al(i), Answer)

            If a.Result = Answer.ResultValue.Correct Then
                correct += 1
            End If
        Next

        Dim score As Double = (correct / questions) * 100
        Label1.Text = score
        SqlDataSource2.Insert()
        Session.Add("DateTimeComplete", DateTime.Now)
        Session.Add("Score", score)
End Sub



Protected Sub resultGrid_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles resultGrid.SelectedIndexChanged
        SqlDataSource1.FilterExpression = "QuestionID=" & resultGrid.SelectedValue.ToString()
    End Sub

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Please help me. Thanks.

What does the grid's markup look like?