[Plugin: WP-FB-comments] Fatal error when activating

I’m getting this when I try to activate plugin:

Fatal error: Cannot redeclare class FacebookApiException in /home/content/12/6950412/html/wp-content/plugins/wp-fb-comments/facebook.php on line 91

I’m running on 5x php. Any suggestions (and dumb it down b/c I don’t know how to code, please).

Thanks

http://ww.wp.xz.cn/extend/plugins/wp-fb-comments/