Okay. Is there anything in your log files?
The part which handles the redirects in that guide is:
try_files $uri $uri/ /index.php$is_args$args;
Make sure you set the directives through nginx (see example here http://www.howtoforge.com/forums/sho...14&postcount=4
) and not by modifying the vhosts file as ISPConfig will overwrite it.