nxhtml 1.21-080322 version can not work

[Ford Guo]

I down the latest version 1.21 for nXhtml,and I remove the 1.20's
directory and unzip 1.21
when I start emacs ,the error are:
Loading /home/agile/.emacs.d/nxml/autostart.el (source)...
Nxml/Nxhtml Autostart.el loading ...
Loading /home/agile/.emacs.d/nxml/nxml-mode-20041004/rng-auto.el
(source)...done
Loading /home/agile/.emacs.d/nxml/nxhtml/nxhtml-autoload.el
(source)...
Loading advice...done
Loading cl-macs...done
Loading url-methods...done


An error has occurred while loading `/home/agile/.emacs':

Assertion failed: (html-site-dir-contains site-root path-in-site)

To ensure normal operation, you should investigate and remove the
cause of the error in your initialization file.  Start Emacs with
the `--debug-init' option to view a complete error backtrace.

And when I use nxhtml-mode the error is:
Loading /home/agile/.emacs.d/nxml/nxhtml/nxhtml.el (source)...
Loading cl-macs...done
Loading easy-mmode...done
Loading rx...done
documentation: Symbol's function definition is void: mumamo-chunk-xml-
pi


any helps?
Thanks
--Ford