Is your main picture setting in "Dynamic" mode? If so, try a different main setting and attempt to adjust the black level settings then.
I just received my new TV. I was trying to calibrate it to custom settings as suggested on another site. I can't access the HDMI black level settings. This option/ choice is grey and I can't choose it. I have my HDMI's running through a receiver so I connected the hdmi direct from the TV to the Direct TV box same thing. How is this feature accessed?