Hi Frank,
Thanks for your help. Unfortunately it worked only on the main page. All other sub pages became unavailable (Content Encoding Error). Tried to refresh permalink but it didn't work either.
Here the output on main page:
AO go: hooking to WP
AO go: config done, switching to buffer
AO go: all done
AO go: going through classes
I had to upload the original again. What a pity...
Anyway, thanks again for all your efforts :)
Thomas