GridView is not shown in the content page in aspx page with Master page

I have a gridview in my aspx page with Master page.

When running the aspx page it's not shown gridview in the content page but on at the top of the aspx page.

And when i deleted gridview and put some simple text in place of it , it's don't working .

Please see this image :

Please help me out.

My code below.

Master page

<%@ Master Language="C#" AutoEventWireup="true" CodeFile="Mpdue.master.cs" Inherits="Mpdue" %>

<!DOCTYPE html>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajax" %>
<html>
<head runat="server">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title></title>
    <asp:ContentPlaceHolder ID="head" runat="server">
    </asp:ContentPlaceHolder>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
            </asp:ContentPlaceHolder>
            <asp:ScriptManager ID="ScriptManager" EnableScriptGlobalization="true" EnableScriptLocalization="true"
                runat="server">
            </asp:ScriptManager>
            <div>
                <div id="generale">
                    <div id="header">
                        <div id="headerLeft">
                            &nbsp;
                        </div>
                        <div id="headerRight">
                            &nbsp;
                        </div>
                        <div class="clear">
                        </div>
                    </div>
                    <div id="login">
                        <div id="loginLeft">
                        </div>
                        <div id="loginCenter">
                            <asp:Label ID="lbWelcome" runat="server">
                            </asp:Label>
                        </div>
                        <div id="loginRight">
                        </div>
                        <div class="clear">
                        </div>
                    </div>
                    <br />
                    <fieldset>
                        <legend style="font-size: 12px; font-weight: bold; color: Red; margin-left: 10px;">
                        </legend>
                    </fieldset>
                    <div id="footer">
                        <div id="footerLeft">
                        </div>
                        <div id="footerCenter">

                        </div>
                        <div id="footerRight">
                        </div>
                    </div>
                </div>
            </div>
        </div>
    </form>
</body>
</html>

aspx page

<%@ Page Title="" Language="C#" MasterPageFile="Mpdue.master" AutoEventWireup="true" CodeFile="sDefault.aspx.cs" Inherits="sDefault" %>

<%@ MasterType VirtualPath="Mpdue.master" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">

    <asp:Panel ID="pngvProducts" runat="server">
        <asp:GridView ID="gvProducts" AutoGenerateColumns="False" EmptyDataText="No data" EnableViewState="true"
            runat="server" DataKeyNames="sID" CssClass="mGrid" Width="500" HorizontalAlign="Center"
            AllowPaging="True" PageSize="15"
            OnPageIndexChanging="gvProducts_PageIndexChanging"
            OnRowDataBound="gvProducts_RowDataBound">
            <AlternatingRowStyle CssClass="altrows" />
            <Columns>
                <%--Column 0--%>
                <asp:TemplateField HeaderText="N." ItemStyle-CssClass="ddl_Class_new" ItemStyle-HorizontalAlign="Center">
                    <ItemTemplate>
                        <%#Container.DataItemIndex + 1%>
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>

            <PagerTemplate>
                <asp:ImageButton ID="ImageButton1" runat="server" ImageUrl="/aspnet/Img/bot_back_doppio.gif"
                    CommandArgument="First" CommandName="Page" />
                <asp:ImageButton ID="ImageButton2" runat="server" ImageUrl="/aspnet/Img/bot_back.gif"
                    CommandArgument="Prev" CommandName="Page" />
                Pagina
                        <asp:DropDownList ID="ddlPages" runat="server" AutoPostBack="True" CssClass="ddl_Class"
                            OnSelectedIndexChanged="ddlPages_SelectedIndexChanged">
                        </asp:DropDownList>
                di
                        <asp:Label ID="lblPageCount" runat="server"></asp:Label>
                <asp:ImageButton ID="ImageButton3" runat="server" ImageUrl="/aspnet/Img/bot_next.gif"
                    CommandArgument="Next" CommandName="Page" />
                <asp:ImageButton ID="ImageButton4" runat="server" ImageUrl="/aspnet/Img/bot_next_doppio.gif"
                    CommandArgument="Last" CommandName="Page" />
            </PagerTemplate>

        </asp:GridView>
    </asp:Panel>
</asp:Content>

Solution

You placed the ContentPlaceHolder above anyhing else, so of course the contents will be above the header. You need to place the ContentPlaceHolder in a position of the Master where you want the content to be placed.

<form id="form1" runat="server">
    <div>
        <div>
            <div id="generale">
                <div id="header">

                </div>
                <div id="login">

                </div>

                <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server"></asp:ContentPlaceHolder>

                <fieldset>
                    <legend style="font-size: 12px; font-weight: bold; color: Red; margin-left: 10px;"></legend>
                </fieldset>

                <div id="footer">

                </div>
            </div>
        </div>
    </div>
</form>