Critical Path - Longest Path won't show as critical

Hi All,

I'm working on a schedule that has a very generous duration and anticipate finishing ahead of schedule.  Therefore my schedule has a lot of float and no activities show as critical.  I'm attemting to use the longest path. However when I select longest path and schedule no activities show as critical. 

After scheduling with the longest path, I filtered by longest path and the only activity that shows up is my substantial completion finish milestone.

Most activities are task dependent with start and finish milestones. 

Any ideas why it won't the longest path as critical?

Thanks.