Make sure that sitebuilder-core package is installed on your server and that sitebuilder3.so file is included into PHP configuration. Something like this on my server:
Try to check directly on the server if module loaded:
# /opt/php51/bin/php5 -m|grep sitebuilder
If it loaded but http://sitebuilder.domain.tld/check.php still displays that sitebuilder3 extensions is not loaded then I guess somehow still not correct PHP loaded for Sitebuilder. This will require investigation on your server so in this case it is better to contact with support team.
and when i issue the command on last dimitry post i get this,
[root@heracles tmp]# /opt/php51/bin/php5 -m|grep sitebuilder
PHP Warning: PHP Startup: sitebuilder3: Unable to initialize module
Module compiled with module API=20060613, debug=0, thread-safety=0
PHP compiled with module API=20050922, debug=0, thread-safety=0
These options need to match
in Unknown on line 0
[root@heracles tmp]#
now if i perform the command from the
[root@heracles ~]# /opt/php52/bin/php5 -m|grep sitebuilder
sitebuilder3
[root@heracles ~]#
but if I run it from the server wide php
[root@heracles tmp]# /usr/bin/php -m|grep sitebuilder
[root@heracles tmp]#