Diagnosis
You tried to make an incorrect assignment between lines and linegroups. There are two possible causes of the error:
1. Lines must be assigned to line groups in increasing order, i.e. theline group must either stay the same or also get larger with increasingline numbers.
2. The assignment is incomplete, i.e. not all the lines were assignedto a line group. You must assign either all the lines of a line groupor none at all.

Procedure
Correct the assignment so that the specified error no longer occurs.