Thread:Extension talk:Cite/the extension cannot run

I already have the "extensions/Cite" directory, and the files are all no problem in the directory. But when I opened the "Special:Version" of my wiki, I found nothing listed in "Installed extensions".

I was also trying to add "require_once("$IP/extensions/Cite/Cite.php");" to the LocalSettings.php, but a 500 Internal Error happened.

My site's URL is

http://www.cjkvbbs.org/hannom/wi/

And my server provider is iPage.

Anyone could solve this problem? Thanks in advance!