how to access page control at master page

protected void Page_Load(object sender, EventArgs e)
{
   Label lbl = (Label)Master.FindControl("ContentPlaceHolder1").FindControl("Label1");
   string test = lbl.Text;
}

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
    <asp:Label ID="Label1" runat="server" Text="yyyyyyyy"></asp:Label>
</asp:Content>