The {0} {1}' has an invalid {2} level at level {3}. Levels within a {2} can only have one ChartMember, unless each member ...

The {0} ‘{1}' has an invalid {2} level at level {3}. Levels within a {2} can only have one ChartMember, unless each member at that level is static (i.e., no Group specified), and static ChartMembers cannot have child ChartMembers.