PmWiki wants setgid permissions enabled on /home/fromhell/straight/www/pmwiki-1.0.13
before it creates the wiki.d directory.
Try executing

    chmod 2777 /home/fromhell/straight/www/pmwiki-1.0.13

on your server and reloading this page. Afterwards, you can restore the permissions
to their current setting by executing

    chmod 755 /home/fromhell/straight/www/pmwiki-1.0.13

If this doesn't work for you, see the link below.

We are sorry for any inconvenience.