[pmwiki-users] Triad fixed width - how to set, please

[kirpi at kirpi.it]

I just installed pmwiki 2.1.6 and triad skin, but I can't find the way
to set it fixed width (and centered).
There is an available link at Site.TriadStyleOptions but nothing
happens as I click on it.
Actually, it says: Page Width Style (disabled by default) so I also set
$EnableStyleOptions = 1;
on config.php but nothings changes.

I also thought that my brosers hax some bugs, but
http://www.pmwiki.org/wiki/Cookbook/TriadSkin?action=set&demostyle=800#styles
works fine...

Where am I wrong, please?
Luigi