Suite 7.0 corner wall cabinet

[JDUB]

In my kitchen, I have 12" deep cabinets on top and 24" deep cabinets on the bottom. The top corner cabinet sits on top of a "garage", which sits on top of the base cabinet. This is the only place in the kitchen that the cabinets are attached from top to bottom. Unfortunately, I have been unable to create this in the tool (designer suite 7.0). The base corner cabinet seems to work ok but the top wall cabinet is not. I can not get the left and right to a value below 24". I assume the right and left means the depth on each side but I am not sure. If that is the case, then it should be 12" so the corner cabinet can attach flush to the cabinet on either side. To complicate things further, I need a flat diagonol door on the front which really gets messed up (becomes a huge bulging round thing larger than the cabinet itself). Any insight would be appreciated. I find the Help feature in the tool to be rather useless. Thank you.