by Alan Hess.
Hello Ute
Are you adding the link in 'a lesson', as a link on the course page or in some edited 'HTML page content'?
Can you activate the HTML <> code display mode in the editor and check if the '<a href='.....> link code is being inserted. Also some themes in Moodle 2 don't show the URL link in blue which can be confusing.
Just out of interest, you may like this 'eBook' software for adding content to Moodle courses. http://stories4learning.com/intro_de
English lesson http://stories4learning.com/moodle/mod/scorm/view.php?id=31
Best regards
Alan Hess