Microsoft project management software used to plan, manage, and communicate a project schedule and other information among workgroup members, project managers, and other stakeholders.
Hello, thank you for your reply.
Actually, I was able to solve the Problem. The Problem is, that by default Projects are saved in the old Project-Format in compatibility mode for Project 2007. New Projects are also by default opened in compatibility mode. After saving the project in a new (2010+) format I was able to use manual task planning.
... very strange, sorry for the inconvenience.
Best
Hugo