As Graphene-Mobile is relying on the Mobile Smart plug-in, I am posting the problem here.
When trying to activate the Mobile Smart plugin, I get
Fatal error: Cannot redeclare class uagent_info in /home/httpd/vhosts/theater-lueterkofen.ch/httpdocs/wp-content/plugins/mobile-smart/lib/mdetect.php on line 66.
Graphene-mobile 1.2.6 (installed but not activated)
Mobile Smart 1.3.1 (which is stated not comaptible to WP 3.5.1)
I have WPTouch 1.9.41 installed but not activated when trying to activate Mobile Smart