Do not forget the form

I think ajax-enabled html needs a form around it to work.
A typical scenario: I put a richfaces tree on the html page with the hope that when i click a node, the content of another area of page is updated (using ajax).
I looked over existing samples on richfaces demo site, and it looked not so complicated. But, as alway...IT DOESN'T WORK ;(
After a while, trying everything out and being quite upset, I changed the switchMode of the tree from "client" to "ajax" just to see what happens.
And I got an error message indicating that this poor tree cannot find its FORM
You can imagine how angry I was, when i realized that i've forgotten to put ... tags arround my page.