Value from previous page not transferring

I have the following code, in which I am trying to transfer some text in a previous page's textbox control (located in the master page) to the same master page textbox control. However it is not working. Please let me know if you can spot the error.

  protected void Page_Load(object sender, EventArgs e)
    {


        if (PreviousPage != null)
        {
            TextBox placeholder =
                (TextBox)PreviousPage.Master.FindControl("TextBox1");
            if (placeholder != null)
            {
                TextBox searchBox = (TextBox)Master.FindControl("TextBox1");
                string search = placeholder.Text.ToString();
                searchBox.Text = search;
            }
        }
    }

this is the .aspx of the master page:

<%@ Master Language="C#" AutoEventWireup="true" CodeBehind="Site1.master.cs" Inherits="AlexBookShop.Site1" %>

<!DOCTYPE html>

<html>
<head runat="server">
    <title></title>
    <asp:ContentPlaceHolder ID="head" runat="server">
    </asp:ContentPlaceHolder>
    <style type="text/css">
        .auto-style1 {
            margin-bottom: 0px;
        }
    </style>
</head>
<body>


    <form id="form1" runat="server">


        <div>

            <asp:DropDownList ID="DropDownList1" runat="server">
                <asp:ListItem Value="1">Children</asp:ListItem>
                <asp:ListItem Value="1">Finance</asp:ListItem>
                <asp:ListItem Value="3">Non-Fiction</asp:ListItem>
                <asp:ListItem Value="4">Technical</asp:ListItem>
            </asp:DropDownList>

            <asp:TextBox ID="TextBox1" runat="server" CssClass="auto-style1"></asp:TextBox>
            <asp:Button ID="Button1" runat="server" Text="Search" OnClick="Button1_Click" />
            <asp:Button ID="Button2" runat="server" Text="Log Out" OnClick="Button2_Click" />

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

    </form>

</body>
</html>

Solution

For transferring data from one page to other page via MasterPAge you need to do cross page posting.

you need to assign the PostBackUrl property of a button control on the first page to point to the second one. like

<asp:Button ID="Button1" runat="server" Text="Button" PostBackUrl="~/Secondpage.aspx"/>
set the PreviousPage directive on the second page:

<%@ PreviousPageType VirtualPath="~/firstpage.aspx" %>

Then whenever second page receives a postback, get the data you need from the first page:

protected void Page_Load(object sender, EventArgs e)
{
    if (PreviousPage != null)
    {
        TextBox placeholder =
            (TextBox)PreviousPage.Master.FindControl("TextBox1");
        if (placeholder != null)
        {
            TextBox searchBox = (TextBox)Master.FindControl("TextBox1");
            string search = placeholder.Text.ToString();
            searchBox.Text = search;
        }
    }
}