DataList、Repeater、GridView中的Checkbox取值问题

先看页面代码

 <asp:DataList id="DataList1" runat="server" Width="100%" RepeatColumns="4" Font-Size="10pt">
         <ItemTemplate>
          <TABLE id="Table2" cellSpacing="0" cellPadding="0" width="100%" bgColor="gainsboro" border="0">
           <TR>
            <TD align="center">
             <asp:Label id=lblOName runat="server" Font-Size="10pt" Text='<%# DataBinder.eval_r(Container.DataItem,"nmenu_name")%>'>
             </asp:Label>
             <asp:Label id=lblID runat="server" Font-Size="10pt" Text='<%# DataBinder.eval_r(Container.DataItem,"nmenu_id")%>' Visible="False">
             </asp:Label></TD>
           </TR>
           <TR>
            <TD align="center">
             <asp:CheckBoxList id="cbSelect" runat="server" Font-Size="10pt" RepeatColumns="2" Width="100%" BackColor="#FFE0C0"
              RepeatDirection="Horizontal" DataTextField="nmenu_tname" DataValueField="nmenu_tid"></asp:CheckBoxList></TD>
           </TR>
          </TABLE>
         </ItemTemplate>
        </asp:DataList>

后台绑定CheckBox:

 private void Page_Load(object sender, System.EventArgs e)
   {
    // 在此处放置用户代码以初始化页面
    if(!IsPostBack)
    {
     if(Session["UID"]!=null&&Session["UID"].ToString()!="")
     {
      BindList();
      BindCheckBox();
     }
     else
     {
      Server.Transfer("error.aspx");
     }
    }
   }
 private void BindList()
   {
    string sql = "select * from NewsOne";
    DataList1.DataSource = ort.ExecuteToTable(sql);
    DataList1.DataBind();
   }
 private void BindCheckBox()
   {
    foreach(DataListItem dli in DataList1.Items)
    {
     CheckBoxList cbl = (CheckBoxList)dli.FindControl("cbSelect");
     Label lbl = (Label)dli.FindControl("lblID");
     string sql = "select * from NewsTwo where nmenu_oid="+lbl.Text;
     cbl.DataSource = ort.ExecuteToTable(sql);
     cbl.DataBind();
    }
   }

CheckBox取值：

 string list = "";
      foreach(DataListItem dli in DataList1.Items)
      {
       CheckBoxList cbSel = (CheckBoxList)dli.FindControl("cbSelect");
       for(int i=;i<cbSel.Items.Count;i++)
       {
        if(cbSel.Items[i].Selected == true)
        {
         list += cbSel.Items[i].Value + ",";
        }
       }
      }
      list = list.Trim(",".ToCharArray());

有的时候会出现取不到值的情况，我的看法是缺少if(!IsPostBack)。