I wonder why the schedule parameter "level" doesnt exist in the list of available fields when I try to list the walls and columns in my project (two different schedules).
For all other objekts in the project (e.g. floors, windows and doors) I can choose "level" as a field and sort objects by level.
The walls are modeled as seperate objects for each floor.
It probably has something to do with walls and columns having 2 level parameters: base level and top level.
It's a pain, but if you really need to seperate them out, phases or worksets usually works pretty well. Alternatively, you could create a new parameter for all walls and columns called "Level for Scheduling" or something, but you would have to manually assign the values to all of the objects.