Repeater控件怎样触发事件？

我这样写的不进断点，知道原因的教下我，最好能说下怎么改
<asp:Repeater runat="server" ID="rep"  OnItemCommand="rep_ItemCommand">
<HeaderTemplate>
<table width="230" border="0" cellpadding="5">
</HeaderTemplate>
<FooterTemplate>
</table>
</FooterTemplate>
<ItemTemplate>
<tr>
<td align="left">
<a href="xinwen.aspx?&id="+ xwid +"">
<%# Eval("xinwenjianjie") %>
</a>
</td>
</tr>
</ItemTemplate>
</asp:Repeater>
－－－－－－－－－－－－－－－－－－－－－－
protected void rep_ItemCommand(object source, RepeaterCommandEventArgs e)
    {
       RepeaterItem it = e.Item;
       DropDownList tb = it.FindControl("xinwenjianjie") as DropDownList;
       Session["wq"] = tb.Text;
       string id = tb.Text;
       SqlConnection conn2 = new SqlConnection(System.Configuration.ConfigurationManager.AppSettings["ConnectionString"].ToString());
       SqlCommand cmd2 = new SqlCommand("select xwID from gongsixinwen where xinwenjianjie='" + id + "'", conn2);
       conn2.Open();
       SqlDataReader sr = cmd2.ExecuteReader();
       sr.Read();
       conn2.Close();
       int xwid = Convert.ToInt32(sr);
       Response.Redirect("xinwen?&id="+ xwid +"");
    }