Macbook Pro screen remains black after opening computer.

When I open my macbook, the screen remains black (as though it's in sleep mode). Adjusting the brightness always fixes this problem, but this is a temporary fix. The brightness is not at zero when I adjust it after opening, often I need to dim the screen to reactivate it.

This problem is not:

• related to *clamshell mode*
• related to unintentionally dimming the screen.
• related to any of the settings in the Energy Saving panel in system preferences

Extra info:

• The computer seems as though it doesn't actually enter sleep mode when I close the computer.
• I don't think there are any processes running that would prevent sleep mode.

I really just want the computer to go to sleep properly when I close the screen and more importantly, that it wake-up when opened, or at least when a button is pushed aside from the brightness buttons.

Thanks.