Cause

The cable length value is not specified for the cable's main function.

Solution

1. Locate the cable's main function in the schematic from the Message management dialog using the Go to (graphic) functionality.
2. There double-click the marked cable definition line and call up the Properties <...> dialog for the cable.
3. If not already set by default, switch to the Cable tab and enter a value in the Length field.
4. Click [OK].
5. If required, start a new check run.