GivdView中CheckBox全选问题
如题，页面有一个id为allChooseCB的全选CheckBox，想实现当勾选后，GirdView1中一列CheckBox全部选中，但是出现了未将对象引用设置到对象的实例，代码如下，请高手看一下，问题出在哪，如何解决？
注：页面使用了母版页adminMain.master 控件放在可编辑模块concent中

前台源码

<asp:GridView ID="GridView1" runat="server" AllowPaging="True" 

                AutoGenerateColumns="False" DataKeyNames="id,id1" 

                DataSourceID="concentSDS" CellPadding="4" ForeColor="#333333" 

                GridLines="None" Width="100%">

                <AlternatingRowStyle BackColor="White" />

                <Columns>

                    <asp:TemplateField HeaderText="选择">

                        <ItemTemplate>

                                <input id="rowCb" type="checkbox" />

                        </ItemTemplate>

                    </asp:TemplateField>

                    <asp:BoundField DataField="id" HeaderText="索引" InsertVisible="False" 

                        ReadOnly="True" SortExpression="id" ItemStyle-Width="5%">

        <ItemStyle Width="5%"></ItemStyle>

                    </asp:BoundField>

                    <asp:BoundField DataField="classifyName" HeaderText="所属类别" 

                        SortExpression="classifyName" ItemStyle-Width="15%" >

        <ItemStyle Width="15%"></ItemStyle>

                    </asp:BoundField>

                    <asp:BoundField DataField="newsTitle" HeaderText="文章标题" 

                        SortExpression="newsTitle" ItemStyl