We just had new cabinets installed and i love them. However, when i look underneath the upper cabinets i can see my wall. We had a corner cabinet installed and it's on both sides (underneath) that you can see our existing wall. Is there something that can be done?

you will have to do a beter job describing the problem-----i have no idea what you are talking about.

You are talking about diagonal cabinet with no under cabinet panel I guess. Do you have under cabinet lighting?