Qlikview's not the problem here. You're using subqueries as columns and one of them is returning more than one row. That simply cannot work. You need to make sure your subqueries return exactly one row. If you run the same sql statement in a tool like Toad or SQL Developer you would get the same error.
What I have found to be easiest is to do this work in sql by creating a view to get the data the way you want it and then just bring the data in from the view using a simple select procedure. Hope this helps!