can we palce div tags inside contentplaceholder in child master page

Question

I have parent master page with two contentplaceholders , later I am added nested masterpage with existing master page .
In that I want two columns in body section parent masterpage contentplaceholder , for that I have taken two div tags, inside each of div tag I had taken two contentplaceholder .

But they are returning master page error saying:

The page contains markup that is not valid when attached to a master page.

Here is my Child master page, is there any wrong I had written

  <%@ Master Language="C#" MasterPageFile="~/Home.Master" AutoEventWireup="true" CodeBehind="Admin.master.cs" Inherits="OnlinePortalWebProject.Admin" %>
   <asp:Content ID="Content1" ContentPlaceHolderID="Parenthead" runat="server">
   </asp:Content>
   <asp:Content ID="Content2" ContentPlaceHolderID="ParnetBody" runat="server">
       <div class="Admin">
           <div class="AdminLeftPanel">
               <asp:content ID="LeftPanel"
                    ContentPlaceHolderID="ChildLeftPanelContnet" runat="server">
               </asp:content>
           </div>
           <div class="AdminRightPanel">
               <asp:content ID="Content3" 
                    ContentPlaceHolderID="ChildRightPanelContnet" runat="server">
               </asp:content>
           </div>
       </div>
   </asp:Content>

Answer 1

Your problem is with the asp:content. As far i can say you cannot use asp:content directly inside asp:content. But In this case your page shoulb be Master Page.

<div class="Admin">
   <div class="AdminLeftPanel">
     <asp:ContentPlaceHolder ID="ChildLeftPanelContnet" runat="server">
     </asp:ContentPlaceHolder>
   </div>
   <div class="AdminRightPanel">
   <asp:ContentPlaceHolder ID="ChildRightPanelContnet" runat="server">
   </asp:ContentPlaceHolder>
   </div>
</div>