I have the same problem and I am taking it back to the store. Unless you hook up an hd box to your tv the black level will stay blacked out and you will not be able to adjust it. Crazy ha! I do not have a cable box or an hd box. I just have a plain coxial cable line hooked up and cannot change the black level. It stays on dark for me. It is too dark. I cannot see night time scenes well. It is going back to the store. I will get another model that you can adjust regardless of whether you have a box or not.
A juvenile question but I can't seem to readjust the black level setting in the picture mode. This step remains untouchable while the other settings allows changes. Any suggestions?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic