ListView1 FindControl未将对象实例化解决思路

ListView1 FindControl未将对象实例化
前台代码

<asp:ListView ID="ListView1" runat="server" DataKeyNames="日期" 

            DataSourceID="SqlDataSource1" onitemcommand="ListView1_ItemCommand">

            <AlternatingItemTemplate>

                <table style="width: 100%;">

                        <tr>

                            <td>

                                <asp:LinkButton ID="LinkButton1" runat="server" CommandName="select"><%# Eval("标题") %></asp:LinkButton>

                            </td>

                            <td style="width: 300px; height: 30px">

                                <%# Eval("日期") %>

                            </td>

                        </tr>

                    </table>

            </AlternatingItemTemplate>

            <EmptyDataTemplate>

                未返回数据。

            </EmptyDataTemplate>

            <ItemSeparatorTemplate></ItemSeparatorTemplate>

            <ItemTemplate>

                <table style="width: 100%;">

                        <tr>

                            <td>

                                <asp:LinkButton ID="LinkButton1" runat="server" CommandName="select"><%# Eval("标题") %></asp:LinkButton>

                            </td>

                            <td style="width: 300px; height: 30px">

                                <%# Eval("日期") %>

                            </td>

                        </tr>

                    </table>

            </ItemTemplate>

            <LayoutTemplate>

                <ul ID="itemPlaceholderContainer" runat="server" style="">

                    <li runat="server" id="itemPlaceholder" />

                </ul>

                <div style="">

                    <asp:DataPager ID="DataPager1" runat="server">

                        <Fields>