RadioButtonList SelectedIndexchanged如果文本很长，则不触发事件

Question

您好，我有一点问题，或者我应该说一个给我带来很多头痛的巨大问题。我在vb.net编写在线考试申请表。我注意到，如果单选按钮的文本非常长，则SelectedIndexchanged事件不会触发。不知道为什么会这样。但是当我减少文本长度时，事件会按预期触发。我需要举办活动，因为这是我如何保存参加考试的参与者的选定答案选择

  Dim i As Integer = CType(Session("i"), Integer)

    Dim index As Integer = rad.SelectedIndex

    ''here am checking if the person has already answered the question

    ''the person has already answered the question so projct answer back

    Dim myAns As New SerializableDictionary(Of Integer, Integer)


    ''am saving back the answer that the idiot has just answerd 
    Dim xml_serializer As New  _
       XmlSerializer(GetType(SerializableDictionary(Of Integer, Integer)))
    Using string_reader As New StringReader(Session("SVEnglish"))
        myAns = DirectCast(xml_serializer.Deserialize(string_reader),  _
            SerializableDictionary(Of Integer, Integer))
    End Using


    If myAns.ContainsKey(i) Then
        myAns.Remove(i)
        myAns.Add(i, index)
    Else
        myAns.Add(i, index)
    End If

    ''saving back to session

    Dim savedAns As String = ""
    Dim xml_serializer2 As New  _
        XmlSerializer(GetType(SerializableDictionary(Of Integer, Integer)))
    Try
        Using string_writer As New StringWriter()
            xml_serializer.Serialize(string_writer, myAns)
            savedAns = string_writer.ToString
            Session("SVEnglish") = savedAns
            string_writer.Close()
        End Using
    Catch ex As Exception
        Stop
    End Try




    Dim selectAnswers As New SerializableDictionary(Of Integer, String)

    Dim xml_serializerAnswers As New  _
         XmlSerializer(GetType(SerializableDictionary(Of Integer, String)))
    Using string_reader As New StringReader(Session("SelAnswerEnglish"))
        selectAnswers = DirectCast(xml_serializerAnswers.Deserialize(string_reader),  _
                SerializableDictionary(Of Integer, String))
    End Using
    If selectAnswers.ContainsKey(i) Then
        selectAnswers.Remove(i)
        selectAnswers.Add(i, rad.SelectedItem.Text)

    Else
        selectAnswers.Add(i, rad.SelectedItem.Text)
    End If



    Dim selAns2 As String = ""

    Dim xml_serializerSavedAnswers As New  _
            XmlSerializer(GetType(SerializableDictionary(Of Integer, String)))
    Try
        Using string_writer As New StringWriter()
            xml_serializerSavedAnswers.Serialize(string_writer, selectAnswers)
            selAns2 = string_writer.ToString
            Session("SelAnswerEnglish") = selAns2
            string_writer.Close()
        End Using
    Catch ex As Exception
        Stop
    End Try
End Sub

这是在selectedindexchanged子例程中运行的代码。 radiobuttonlist从数据库中填充。任何帮助或建议都非常感谢