LMP versus System Load curve, as well as system status trajectory curve, may exhibit significant change in curve pattern at some load levels, called Critical Load Levels. Majority of the critical load levels can be identified through an established criterion which is defined on marginal unit set and congested branch set. However, exceptions have been observed in a revised IEEE 118-bus system where the existing criterion fails to identify a CLL. A detailed case study has been performed around the missing CLL. Study shows that this CLL is caused by status change in generator reactive power constraint and voltage magnitude constraint. Results suggest to expand the existing criterion to include the generator reactive power constraint in order to capture potential missing CLLs.