Wikimedia Bugzilla is closed!

I have a 1.8 install of mediawiki. I have following the install docs for
CategoryTree and all seems to be working like the Special Page for CategoryTree.

Main issue I am seeing is that when I place my tag in a new or currently used
page like this.

<category>documents</category>

I get the following

[-]documents
  [+]IT Documents

now when I try to click the + I don't see anything other than "loading"

when I tail -f logs/httpd/error.log I see the following

 PHP Fatal error:  Class 'AjaxResponse' not found in
/var/www/html/wiki/extensions/CategoryTree/CategoryTreeFunctions.php on line 92

the above line in the php file is.

this is the first line - $response = new AjaxResponse();

the below is what comes right after the above line in the php file

                if ( $response->checkLastModified( $touched ) ) {
                        return $response;
                }