Cause

Several parts have been assigned to one planning object. As a result, there are also several potential main functions under the function templates. Potential main functions are main functions whose function definitions are preset with the "Main function" attribute. This preset attribute cannot be changed.

A planning object can have only one potential main function.

Solution

1. Locate the planning object in question in the project using the Synchronize selection function offered by the popup menu in the Message management dialog.
2. In the pre-planning navigator, open the Properties <...> dialog of the planning object, and bring to front the Part tab.
3. Delete all unnecessary parts, so that at the planning object only one part with a unique potential main function remains.
4. Click [OK] to close the Property dialog, then start a new project check.