Question about StartDate and Relations

I have a problem with the StartDate. When i set the StartDate of the project to 1.1.2006 all Tasks which haven't a relation have the StartDate of the Project (1.1.2006) althought i set another StartDate to the Tasks (like Task.Start = new system.datetime(2006,1,4) ). I don't know now if all Taks must have a relation or if there is another way to show the right Startposition of those Tasks who haven't a relation. I hope you can help me.

P.S. Sry if my explanation is bad but my english is poor Wink [;)]

Edit: Ok i fount out that it has something to do with the Constrainttype. I tryied the ConstraintType MSO (Must Start on) i think so it takes the StartDate from the Task but i'm not shure so i hope someone can help me what ConstraintType i need to take the StartDate from the Tasks