Add Custom User Control To Published Web Project

I have a published web project. I want to add some .ascx files (with .cs & designer.cs files) to that published web site. These are simple custom user controls that access methods already part of the original application. Question? Is it possible to just drop these in the published web project without building the entire solution? If not why? When I drop these files in and run my application I get the error: "Parse Error: Could not load type 'the name of my custom controls namespace'". There is not a lot of code to show so this is all I have.

Default.aspx
<%@ Page Language="C#" MasterPageFile="~/MasterPages/TwoColumn.master" AutoEventWireup="true"
Inherits="ApplicationName.Web.Default" CodeBehind="Default.aspx.cs" %>
<%@ Register TagPrefix="uc1" TagName="CustomControl" Src="~/Controls/Custom/CustomControl.ascx" %>
<asp:Content ID="content" contentplaceholder="cph" runat="Server">
<uc1:CustomControl ID="cc1" runat="server" CustomProperty="Hello World" />
</asp:Content>
CustomControl.ascx
<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="CustomControl.ascx.cs"
Inherits="ApplicationName.Web.Controls.Custom.CustomControl" %>
<asp:PlaceHolder ID="ph1" runat="server></asp:PlaceHolder>
CustomControl.ascx.cs
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace ApplicationName.Web.Controls.Custom
{
public partial class CustomControl : System.Web.UI.UserControl
{
///My logic
}
}


Again it seems so easy. What am I missing? Or is this not possible?