Thanks a lot for your replies ! Sorry, it was my own mistake, but you helped me to find it, because I collect more information to give you a better description what happens.
We´re set a few weeks ago a filter with plugin optimizer and on some pages BuddyPress was just deactivated.. That´s the only reason.. Now it works !
I think the content looks pretty nice with WPtouch on Smartphones and tablets. WPtouch has one cool feature: you can disable plugins that you don´t wanna use on mobile devices and if I understand it right, you can break down the content a little bit?
You say BuddyPress isn´t 100% responsive, but is it possible to fix the Layout issues just with css? I´m really good with css, but I´m not very familiar with php and javascript..
What´s up with BuddyPress Mobile? Can´t find it anywhere. Is this an alternative?
Do you have any experience with “WP Mobile Detector Mobile Plugin – Pro”?