Problem to Link button

Hi,
There is Link button below, to the GV

        <asp:GridView ID="gvResult" runat="server" 
            CellPadding="4" ForeColor="#333333" Font-Size="12px" 
            AutoGenerateColumns="False" PageSize="20" 
            DataKeyNames="id"
            style="margin-top: 1px" AllowPaging="True" 
            onpageindexchanging="gvResult_PageIndexChanging" 
            OnRowDataBound="gvResult_RowDataBound" onrowcommand="gvResult_RowCommand">
            <PagerSettings Mode="NumericFirstLast" />
            <RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
            <Columns>
                <asp:TemplateField ShowHeader="False">
                    <ItemTemplate>
                        <asp:LinkButton ID="lbEdit" runat="server" CausesValidation="False" 
                            CommandName="RowEdit" Text="更改資料" CommandArgument='<%# Eval("Id") %>'></asp:LinkButton>
                            
                        <asp:LinkButton ID="lbEdit2" runat="server" CausesValidation="False" 
                            CommandName="RowEdit2" Text="更改資料" CommandArgument='<%# Eval("Id") %>'></asp:LinkButton>
                    </ItemTemplate>
					...

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when running the page, the Link button is not shown. But I cannot find out any codes, which are hiding such Link button. Why?