'getEditor': object is null or undefined in an ASP.NET web application with CKEditor 4.4..

Getting this error when debugging a page in which I have placed the 4.4 CKEditor:

Unhandled exception in ../ckeditor/ckeditor.js

'getEditor': object is null or undefined.

I have installed CKEditor into my application exactly as the 4.4 instructions suggest. I then call it like this:

<asp:TableCell CssClass="tablecellBlue">
                <asp:TextBox ID="HTMLEditorBody" TextMode="MultiLine" runat="server" Height="300" Width="875" Columns="50" Rows="20"></asp:TextBox>
                <script>
                    //Replace the <textbox id="HTMLEditorBody"> with a CKEditor instance, using the default configuration. PCG. 05132014
                    CKEDITOR.replace('HTMLEditorBody');
                </script>
            </asp:TableCell>

Any ideas? This is the JQuery based CKEditor 4.4 that was just released in April 2014.