First, I love the game. It's definitly the best sim game on the PocketPC available, probably the best game at all! Well, in my opinion. It's great!
However, I have the same problem with my units having 'Unit is not easily accessible'.
First I made a little statup with a Burger Joint and some condo's:

It' pretty okay so far. However, I decided to make offices on top and to the right of these condo's. I placed a restroom on every level (just in case) and build some offices and escalators. After 2 days or so all the offices start to abandon because of the 'Unit is not easily accessible' (well, at least I think it's because of this). See:

Any hints? Did I completely missed something? HELP!
Eric Kok
NB: I also posted this on the www.esoftinteractive.com forums. I hope you don't mind.