Certain Parts of my Face Just Wont Get Lighter?

Hello, I am African-American, and my skin (on my face and neck) has gotten very dark from sun exposure. I have tried different skin lightening creams over the years, and they do lighten my skin BUT certain areas of my face and neck still remain dark. Particularly the skin above my upper-lip, my neck and eyelids always remain dark, while the other parts of my face get lighter, so i have multi-tone look. What could be causing this and what can I do to solve it?