Ah!!!! I can make such stupid mistakes in Wicket

After copying the 11 files and gazillion lines of code to implement my category tree checkbox, I was see the ol'

WicketMessage: The component(s) below failed to render. A common problem is that you have added a component in code but forgot to reference it in the markup (thus the component will never be rendered).
1. [MarkupContainer [Component id = checkbox]]
I looked and looked at it, I uncommented my "checkbox" from being added, and this caused the error to go away.  I verified that I had a "checkbox" in my html template, but still, whenever I tried to add a checkbox to the tree, I would get the above error.
Finally...  I added a "hello" to my html template and figured out that my template was not even being used.  On further inspection, I find that I had mistakenly named "CheckBoxIconPanel.html" as "ChechBoxIconanel.html"
I wanted to hit my head against my keyboard!
I implemented the checkbox tree described here.  Thanks for it.