User Control as Widget in External Assembly

I am trying to create a widget as a User Control by referencing the documentation located here.  The user control is in a
separate assembly created as a web app and the .ascx file has a build action of Embedded Resource.  This assembly is added as a reference to the Sitefinity project.  I registered the user control widget with the following values:

ControlType: CustomControls.Widgets.CustomCalendarUserControl.CalendarControl.ascx, CustomControls
Name: CalendarControl.ascxc
Title: Custom Calendar

I left the rest of the fields empty.

When I try to drag and drop the control onto a page I get the following error:
Type "CustomControls.Widgets.CustomCalendarUserControl.CalendarControl.ascx, CustomControls" cannot be resolved.

Am I registering the user control widget incorrectly or do I need to do something differently if the user control widget is in an external assembly instead of in the Sitefinity project?

Thanks

Hello Geoff,

If you want to work with a class library, please create a class and implement ITemplate for it, then register the custom class. If you use a user control, you can add it to a folder of the web application and register the control as described in this article.

Kind regards,
Ivan Dimitrov
the Telerik team

I added the ITemplate interface to my user control and implemented it.  The user control is still in an external assembly and I am still receiving the same error.  Is it not possible to register a user control that exists in an external assembly?  Does it have to be contained in the sitefinity web app project?

Also, I was not able to get the link that you posted to work.  Would you mind reposting it?

Thanks.