There could be several causes for this error, so we can cover the most common here, but you may need to contact us for personal support if this does not resolve the issue on your computer. The most common cause is if the software program icon was dragged out of its default installation location in your Applications folder. This might have been done to have a shortcut on the Desktop, but it causes the software to lose track of important files it needs to run.
If that is what happened, open the Applications folder. This is an important location on your computer, with an icon in your Dock by default, so it's easy to find. Inside there, you will find a folder with the name of the software program you're using: Ritmos, Auf geht's!, or Weiter geht's!. Open this folder and drag the program icon inside. Then try running it again, and it should work now.
If you'd like a shortcut for opening the program, you can anchor the software to your Dock without any trouble.
If this did not fix the problem for you, please fill out a support ticket for personalized assistance.