note 69572 added to function.mb-internal-encoding

I'm using php5 and when I try to run this script : mb_internal_encoding("UTF-8"); I gat a fatal error ! Fatal error: Call to undefined function: mb_internal_encoding() in .... what's going on! ---- Server IP: 66.163.161.117 Probable Submitter: 63.243.163.197 (proxied: 172.30.11.69) ---- Manual Page -- http://www.php.net/manual/en/function.mb-internal-encoding.php Edit -- https://master.php.net/note/edit/69572 Del: integrated -- https://master.php.net/note/delete/69572/integrated Del: useless -- https://master.php.net/note/delete/69572/useless Del: bad code -- https://master.php.net/note/delete/69572/bad+code Del: spam -- https://master.php.net/note/delete/69572/spam Del: non-english -- https://master.php.net/note/delete/69572/non-english Del: in docs -- https://master.php.net/note/delete/69572/in+docs Del: other reasons-- https://master.php.net/note/delete/69572 Reject -- https://master.php.net/note/reject/69572 Search -- https://master.php.net/manage/user-notes.php