AutoCAD .NET :: Spaces And Classifications

How exactly you add an Classification to an Space Object(and by Classification i mean the part under Space object properties>Extended Data>Classifications where normally the SIS one is located).

I'm trying trough .NET (C# to be specific) to change the information on a space with something from the Classification Definitions specified in the drawing. I'm able to read the data from the current ones, however if any of the classifications is using the Default(By style) value the space.ClassficationCollection doesn't contain that particular Classification.

In the document i've got a classification definition for spaces called "Space function" and an assorted list of various functions the space itself can be assigned, like Elevetor-shaft, Bathroom/Shover etc.

How to do this or tell if it's impossible to do, Sample below show on how i'm currently getting the information on the space:

Entity ent = (Entity)tr.GetObject(Objectid, OpenMode.ForWrite);     
//Space
Autodesk.Aec.Arch.DatabaseServices.
Space sp = ent as Autodesk.Aec.Arch.DatabaseServices.Space;
[code]........

The code above just shows the classifications that are not using default values.

Software i'm working with is: Autodesk Autocad MEP 2012.