CheckedChanged Event is not firing

I am creating a checkbox dynamically.. my checked changed event is not firing up, any ideas? I

protected void ddlScheme_SelectedIndexChanged(object sender, EventArgs e)
  {
var cbAllWeeks = new CheckBox {Text = entireMonth, AutoPostBack = true};
cbAllWeeks.CheckedChanged += cbAllWeeks_CheckedChanged;

}

protected void cbAllWeeks_CheckedChanged(object sender, EventArgs e)
{
   /////......
   //// More Code
}