@victorbw, i found it out by myself. My Apache config was a little bit too restrictive:
`Header always set X-Frame-Options DENY`
After removing it, everything was fine 
Anyway many thanks!
@victorbw, i found it out by myself. My Apache config was a little bit too restrictive:
`Header always set X-Frame-Options DENY`
After removing it, everything was fine 
Anyway many thanks!