found error

[ayamgore]

hello all,

i have download new version of FAS 4.0

i have install it.

but i have found error when create a directory video and how to add video

http://prntscr.com/1o90pb
http://prntscr.com/1o90ve
http://prntscr.com/1o90y9

Fatal error: Call to undefined function mb_strtolower() in /home2/widimarb/public_html/include/functions_encode.php on line 20

i can't add any videos.
how is the solve ?

Thanks