I deed according to this article https://www.digitalocean.com/community/articles/how-to-install-ispconfig3-on-an-ubuntu-14-04-server as I said all normal html files works on server. But when it comes to Drupal, it does not work, eg. 1) when I activate module, it gets does not activate first, it shows blank screen, then when I refresh page it gets activate. 2) when edit conents ckeditor modules does not work, it stops but while adding contents it ckeditor module work. 3) even some modules does not work like backup & migrate module We are using drupal 7. is it related to path of the server of website or .htaccess please guide me for the same.