“Type or namespace name could not be found” in UserControl Checkbox [on hold]

I already included

using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

but I still keep on receiving this error

Error 2 The type or namespace name 'Checkbox' could not be found (are you missing a using directive or an assembly reference?)

on this block of code

Checkbox[] checkboxes = new Checkbox[] { bagongLipunan, sanRoque, sanRafael, Tanza, Maharlika, Magsaysay };

My code looks great but MS VS keeps on throwing the error. I'm not sure why. The project is in ASP.NET Web Forms, by the way.

Thanks in advance for helping me in my C# blues!