Thread:Extension talk:MobileFrontend/PHP Fatal error: Call to undefined method DeviceProperties::moduleName()

After installing the extension with git and adding required lines to LocalSettings.php file, my Wiki pages are disappeared. The error log shows lots of the occurrences of the same error:

[Sat Feb 16 16:31:18 2013] [error] [client IP] PHP Fatal error: Call to undefined method DeviceProperties::moduleName in /home/mysite/domains/wiki.mysite.com/public_html/extensions/MobileFrontend/includes/skins/SkinMobile.php on line 317

and line 317 in SkinMobile.php has the following line:

if ( $device->moduleName ) {