从 repeater中获取Dropdownlist 和 button

[Element]

这里是页面使用的是repeater 我想获取 按钮控件可是就是取不到
<asp:Repeater ID="rptUserManage" runat="server" OnItemCommand="rptUserManage_ItemCommand">
<HeaderTemplate>
<table>
<tr align="left">
<td colspan="11">
<asp:DropDownList ID="ddlUserRole" runat="server" Width="150px">
</asp:DropDownList>
<asp:Button ID="btnUp" runat="server" Text="启用用户" />
<asp:Button ID="btndown" runat="server" Text="禁止用户" />
</td>
</tr>
<tr align="center" style="background-image: url('../Images/cnn/userManagetop.jpg');
color: White;">
<th>
Id</th>
<th>
用户名</th>
<th>
联系电话</th>
<th>
密码</th>
<th>
姓名</th>
<th>
地址</th>
<th>
电子邮件</th>
<th>
用户状态</th>
<th>
用户角色</th>
<th>
操作</th>
<th>
<input id="chkAll" type="checkbox" runat="server" onclick="SelectAll(this)"/>
全选</th>
</tr>
</HeaderTemplate>
<ItemTemplate>
<tr style="background-color: #FFFF99">
<td>
<%#Eval("Id") %>
</td>
<td>
<%#Eval("LoginId") %>
</td>
<td>
<%#Eval("Phone") %>
</td>
<td>
<%#Eval("LoginPwd") %>
</td>
<td>
<%#Eval("Name") %>
</td>
<td>
<%#Eval("Address") %>
</td>
<td>
<%#Eval("Mail") %>
</td>
<td>
<%#Eval("UserState.Name") %>
</td>
<td>
<%#Eval("UserRole.Name") %>
</td>
<td>
<asp:LinkButton ID="btnDelete" runat="server" Text="删除"></asp:LinkButton></td>
<td>
<input id="chkItem" runat="server" type="checkbox" /></td>
</tr>
</ItemTemplate>
<AlternatingItemTemplate>
<tr style="background-color: #FFFFE6">
<td>
<%#Eval("Id") %>
</td>
<td>
<%#Eval("LoginId")%>
</td>
<td>
<%#Eval("Phone") %>
</td>
<td>
<%#Eval("LoginPwd") %>
</td>
<td>
<%#Eval("Name") %>
</td>
<td>
<%#Eval("Address") %>
</td>
<td>
<%#Eval("Mail") %>
</td>
<td>
<%#Eval("UserState.Name") %>
</td>
<td>
<%#Eval("UserRole.Name") %>
</td>
<td>
<asp:LinkButton ID="btnDelete" runat="server" Text="删除"></asp:LinkButton></td>
<td>
<input id="chkItem" runat="server" type="checkbox" /></td>
</tr>
</AlternatingItemTemplate>
<FooterTemplate>
</table>
</FooterTemplate>
</asp:Repeater>


cs.里面的文件是
Button btnDel = rptUserManage.FindControl("btnDelete") as Button;
Response.Write(btnDel.Text);

报错 System.NullReferenceException: 未将对象引用设置到对象的实例。

[wuyq11]

http://www.cnblogs.com/duhongyu216/articles/1178669.html
http://www.cnblogs.com/345563452/archive/2009/03/19/1417037.html

[pdsnet]

  if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
ButtonButton1= RP_NewList.Items[i].FindControl("SDID") as Button;
}

[cpp2017]

应该用RepeaterItem来FindControl

[Element]

谢谢了，辛苦了大家！
呵呵