Constraints in P6

I'm semi-new to P6.

I'm trying to hold a date in my schedule.  In the bottom activity box I have the dates selected that I want to hold, but in the schedule the * does not appear.  When I update the schedule, it changes all 100% completed dates to the data date.  If I change the data date, it changes all 100% done activities to that data date.

Any input would be apreciated.

Dave