More Awesome Than You!

I just changed a residential lot into a 4 unit apartment.  The first 3 units are fine however, the 4th one on top floor is only going for $125 while the other 3 are around $1200.  Thinking my sim just got a wonderful bonus, since he could still use everything in the apartment, I continued my game, until he rolled wants for basic things like a toilet, tub and fridge which are all provided in the apartment.  I tried to place another toilet just to see if the want would roll away.  I couldn't place anything in the unit.

Quick description of the unit itself:
-Loft style
-techinically, it's on 2 floors but the bottom floor just goes to the stairs that lead up to the loft
pic #1 (http://i7.photobucket.com/albums/y287/cassie341/Lookatme/Sims-100214-171839001.png), pic #2 (http://i7.photobucket.com/albums/y287/cassie341/Lookatme/Sims-100214-171850001.png)

I want to know if this unit can be used properly as an apartment or does the game have an issue with stages and stairs in apartments.

Sounds like a large portion of your apartment is not actually considered to be in the bounds of the apartment.  Did you use floor dividers at all when building it?  Actually, I've occasionally had this problem for no reason with apartments that were downloaded (and not missing doors due to non-packaged CC), and what fixed them was shift-clicking on the door and clicking "recalculate rent". 

My suggestion: move all sims out of the apartment, enter in build mode to make sure that there aren't missing doors or floor dividers, bring in a test sim and try recalculating the rent.  I actually have a spare sim in the bin that I use exclusively for testing out downloaded apartments and making sure they work first.

I made sure I had checked for the floor dividers and made sure they were gone when I started changing the lot over.  I'll double check and try to get the rent recalculated.

It is the stage you used for the divide in the stairs. I had the same problem once. Make the stairs go all the way directly to the second floor instead, or replace with a spiral staircase.

Yes, this is an issue that was discovered shortly after the community got hands on AL. A modular stairs/stage combination only works in one configuration in the neighborhood. In all other configurations, the upper floor is considered community space. You won't be able to move objects around upstairs and without appropriate hacks, you will have neighbors jonesing for your things up there.

One fix is, as Tarlia said, to replace with a straight flight of stairs or a spiral. Another is to build a test lot and experiment with directions on your stair/stage combinations until you find the one that works, then rebuild this apartment. For me, I had to have the stairs parallel to each other and along a particular axis.