Cannot find Checkbox controls in page

I am trying to take the Checkboxes on the page and insert their Text into the database. When I click the submit button it doesn't find any of the Checkbox controls. I am trying to enumerate through all of them and insert each. I need to use individual checkboxes rather than a checkboxlist for this project in case someones suggests I use a list. Why aren't my controls showing up?

C# - Submit button

foreach (Control c in Page.Controls)
{
  foreach (Control childc in c.Controls)
  {
    if ((childc is CheckBox) && ((CheckBox)childc).Checked)
    {
       cmd.Parameters.Clear();
       cmd.Parameters.AddWithValue("@Name", ((CheckBox)childc).Text);
       cmd.Parameters.AddWithValue("@DateAdded", DateTime.Now.ToString());
       cmd.ExecuteNonQuery();
     }
  }
}

C# - Where checkboxes are created and inserted into panel

foreach (System.Xml.XmlNode node in nodes)
{
   string displayname = node.SelectSingleNode("FName").InnerText.Trim();
   string idnumber = node.SelectSingleNode("idNum").InnerText.Trim();
   CheckBox ckBox = new CheckBox();
   ckBox.InputAttributes.Add("value", idnumber);
   panel1.Controls.Add(new LiteralControl("<div class='checkbox checkbox-slider-lg checkbox-slider--b-flat'><label>"));
   panel1.Controls.Add(ckBox);
   panel1.Controls.Add(new LiteralControl("<span>" + displayname + "</span></label></div>"));
}

All of my checkboxes are dynamically inserted into this panel on my page

.ASPX

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
   <form id="form1" runat="server">
       <asp:Panel ID="panel1" runat="server"></asp:Panel>
       <asp:Button ID="btn1" runat="server" OnClick="Submit_Click" Text="Save" />
   </form>
</asp:Content>

Also tried this but it didn't pick up the controls either:

foreach (var ctrl in this.Controls.OfType<CheckBox>().Where(x => x.Checked))