Trying to load User Control in Web Part, getting "Object Reference not set" error

Hello,

I am using Visual Studio 2012 to create a web part for SharePoint 2010, which will consume a User Control. I am coding in C#. In the User Control, I have designed my web part with various controls from the toolbox. I created the user control itself following the steps in this article:

http://msdn.microsoft.com/en-us/library/vstudio/ee231548(v=vs.110).aspx

And I am setting up my web part .cs file to use the User Control following the example in this article:

http://msdn.microsoft.com/en-us/library/vstudio/ee231577(v=vs.110).aspx

The code in my web part .cs file now looks like this:

        private const string _ascxPath = @"~/_CONTROLTEMPLATES/UpdatePanelTestv2/ChartUserControl.ascx";

        protected override void CreateChildControls()
        {
            base.CreateChildControls();
            Control control = Page.LoadControl(_ascxPath);
            Controls.Add(control);            
        }

When I debug this code, I get unhandled HttpParseException error, 'Object Reference not set to Instance of an Object. on the line "Control control = Page.LoadControl(_ascxPath);"

How can this be? I'm declaring both 'control' and _ascxPath, and stepping through the code in the debugger doesn't show the compiler going anywhere after that line before throwing the error.

I get the same thing if I use "this.Page.LoadControl" also. What gives?

Any help will be greatly appreciated.