"Overall Statistics" and "posts/questions" Issues in EasyDiscuss Backend

Hello,

I have 2 errors in the easydiscuss bakcend of my site :
- In the "Overall Statistics" and "posts/questions" pages
see attached picture.

Many Thanks for your help
Best Regards
Arnaud

System Information
EASYDISCUSS version 4.0.7
PHP Built On Linux info 3.0 #1337 SMP Tue Jan 01 00:00:00 CEST 2000 all GNU/Linux
Database Version 5.1.73-1+deb6u1
Database Collation latin1_swedish_ci
Database Connection Collation utf8_general_ci
PHP Version 5.5.38
Web Server Apache
WebServer to PHP Interface cgi-fcgi
Joomla! Version Joomla! 3.6.2 Stable [ Noether ] 4-August-2016 23:41 GMT
Joomla! Platform Version Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT
User Agent Mozilla/5.0 (Windows NT 10.0; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0