Fatal error from membership plugin

I recently moved my site to a new sever via a mysql database export/import and ftp file transfer. Everything is working fine except for the membership plugin. I am getting a fatal error:

Fatal error: Call to undefined function mb_stripos() in /home/businessdeacon/public_html/entrepreneurs/wp-content/plugins/membership/membershipincludes/includes/functions.php on line 1027

Through my own troubleshooting, I have found that it seems the issue is with the "url groups". It seems that when I enable 1 or more in the plugin I get the error. If I do not use url groups then I get no error. I have been using this entire setup on this site successfully with no issues until the move of the site. The move was server only, the domain stayed the same. And lastly, not sure if this has anything to do with it but this site is a subfolder install (main domain -www.smallbusinessdeacon.com- is html and this wordpress install is sub folder -/entrepreneurs)
http://www.smallbusinessdeacon.com/entrepreneurs

Just looking for a little help on troubleshooting this issue. Right now I have no url groups enabled so there is no error on the site. If you need login creds, just let me know. thanks.