PHP Fatal error: Class 'ExSimpleXMLElement'

I install the latest version of xerte (Last update 2016-02-19) - from xert.org.uk - no errors during the installation.
Still the same problem.
After the installation re-copy /editor/upload.php file and upload again.
Still the same problem.
Also send you again: tail /var/log/apache2/error.log
[Mon Feb 22 20:18:12.230834 2016] [:error] [pid 7226] [client 127.0.0.1:37487] PHP 1. {main}() /var/www/html/xerte/editor/upload.php:0, referer: http://localhost/xerte/edithtml.php?template_id=3
[Mon Feb 22 20:18:12.230855 2016] [:error] [pid 7226] [client 127.0.0.1:37487] PHP 2. process() /var/www/html/xerte/editor/upload.php:50, referer: http://localhost/xerte/edithtml.php?template_id=3
[Mon Feb 22 20:18:14.798754 2016] [:error] [pid 7228] [client 127.0.0.1:37488] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /var/www/html/xerte/editor/upload.php on line 171, referer: http://localhost/xerte/edithtml.php?template_id=3
[Mon Feb 22 20:18:14.798853 2016] [:error] [pid 7228] [client 127.0.0.1:37488] PHP Stack trace:, referer: http://localhost/xerte/edithtml.php?template_id=3
[Mon Feb 22 20:18:14.798950 2016] [:error] [pid 7228] [client 127.0.0.1:37488] PHP 1. {main}() /var/www/html/xerte/editor/upload.php:0, referer: http://localhost/xerte/edithtml.php?template_id=3
[Mon Feb 22 20:18:14.799037 2016] [:error] [pid 7228] [client 127.0.0.1:37488] PHP 2. process() /var/www/html/xerte/editor/upload.php:50, referer: http://localhost/xerte/edithtml.php?template_id=3
[Mon Feb 22 20:18:20.230734 2016] [:error] [pid 7229] [client 127.0.0.1:37489] PHP Fatal error: Class 'ExSimpleXMLElement' not found in /var/www/html/xerte/editor/upload.php on line 171, referer: http://localhost/xerte/edithtml.php?template_id=3
[Mon Feb 22 20:18:20.230834 2016] [:error] [pid 7229] [client 127.0.0.1:37489] PHP Stack trace:, referer: http://localhost/xerte/edithtml.php?template_id=3
[Mon Feb 22 20:18:20.230922 2016] [:error] [pid 7229] [client 127.0.0.1:37489] PHP 1. {main}() /var/www/html/xerte/editor/upload.php:0, referer: http://localhost/xerte/edithtml.php?template_id=3
[Mon Feb 22 20:18:20.231007 2016] [:error] [pid 7229] [client 127.0.0.1:37489] PHP 2. process() /var/www/html/xerte/editor/upload.php:50, referer: http://localhost/xerte/edithtml.php?template_id=3

And all the phpinfo.php:

Thanks a lot,
Elias

Sorry, i have no other suggestions than there is something wrong with your SimpleXML module... are you hosting anything else on that box that uses php? Is that working correctly?

John

"are you hosting anything else on that box that uses php?"
yes, tcexam and openeclass.
"Is that working correctly?"
yes, both of them.
I deleted xot 3.1 (all files in /var/www/html/xerte and mysql xerte base/tables) and then I installed the xot 3.0 the same error. I deleted xot 3.0 and then I installed xot 2.1.
The xot 2.1 works perfect!!!!!
Also I installed today xot 3.1 to another linux machine (ubuntu 12.04) and it worked perfectly.

Thanks a lot,
Elias