考试系统,repeater 中嵌入radiobuttonlist 并绑定的问题

Protected Sub rptQuestion1_Itemdatabound(ByVal s As Object, ByVal e As System.Web.UI.WebControls.RepeaterItemEventArgs)
        Dim dtselect As DataTable
        Dim dtcolumn As DataColumn
        Dim dtrow As DataRow
        dtselect = New DataTable("select")
        '创建一列
        dtcolumn = New DataColumn("select", GetType(String))
        dtselect.Columns.Add(dtcolumn)
        '添加一行
        Dim i As Integer
        For i = 0 To 5
            dtrow = dtselect.NewRow
            dtrow("select") = "1"
            dtselect.Rows.Add(dtrow)
            dtrow = dtselect.NewRow
            dtrow("select") = "2"
            dtselect.Rows.Add(dtrow)
        Next
        Dim rb As RadioButtonList = New RadioButtonList
        rb = CType(e.Item.FindControl("rbl2"), RadioButtonList)

        rb.DataSource = dtselect
        rb.DataTextField = "select"
        rb.DataBind()
        ' rbl1.DataSource = rb
        '  rbl1.DataTextField = "select"
        ' rbl1.DataBind()
        Response.Write("dddd")
    End Sub

但是却出现错误

Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Line 641:        rb = CType(e.Item.FindControl("rbl2"), RadioButtonList)
Line 642:
Line 643:        rb.DataSource = dtselect
Line 644:        rb.DataTextField = "select"
Line 645:        rb.DataBind()

--------------------编程问答-------------------- 路过帮顶
=============
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http://topic.csdn.net/u/20081107/11/b27dc75f-14b1-4594-9de3-5b18d9e36a11.html
此次调整增加了两个新的可用分获取渠道：
1：帖子被推荐（加精）后，帖主可以获得88分的可用分奖励；
2：帖子结帖后会返还帖主50%的悬赏分，无满意结帖不返还分数；
3：接下来会不断增加新的可用分获取途径，比如参与活动赠送等，请大家多关注； --------------------编程问答-------------------- VB? --------------------编程问答-------------------- Dim rb As RadioButtonList = New RadioButtonList
rb = CType(e.Item.FindControl("rbl2"), RadioButtonList)

看看查找到的rb是不是为null --------------------编程问答--------------------

你的"select" 上面的是变量到下面变成字符串了。。。。rb.DataTextField = 字符串当然会出错 --------------------编程问答-------------------- rb = CType(e.Item.FindControl("rbl2"), RadioButtonList)
----------------------------------------------------------
这里是不是没有找到控件

补充：.NET技术 ,  ASP.NET