Adding a new Web Content Form to a Nested Master Page not displaying Content Area.

I have a nested master page with following code:
<%@ Master Language="C#" MasterPageFile="~/master1.Master" AutoEventWireup="true" CodeBehind="NestedMasterPage1.master.cs" Inherits="FlexStock.NestedMasterPage1" %> <asp:Content ID="NestedContent1" ContentPlaceHolderID="head" runat="server"> </asp:Content> <asp:Content ID="NestedContent2" ContentPlaceHolderID="MasterContentArea" runat="server"> </asp:Content>
When I open the nested master page at design time, it shows the content area. But when I add a new Web Content Form and set master page to this nested master page, the new Web Content Form doesn't have any content area. It just displays one line:
<%@ Page Title="" Language="C#" MasterPageFile="~/NestedMasterPage1.master" AutoEventWireup="true" CodeBehind="selectCompany.aspx.cs" Inherits="FlexStock.Forms.selectCompany" %> Why the content ar ...