Fatal error: Call to undefined function mb_regex_encoding() in /home/ohafiahe/pu

Fatal error: Call to undefined function mb_regex_encoding() in /home/ohafiahe/public_html/components/com_k2/helpers/route.php on line 94

I needed help to overcome this problem

My Host Reply me when i requested for mb_regex_encoding to be enabled
The mb_regex function is enabled on the server. This is the content of the error display on the screen as I loaded your site:
Fatal error: Call to undefined function mb_regex_encoding() in /home/ohafiahe/public_html/components/com_k2/helpers/route.php on line 94
This is coding error.