I have a dual graphics card: intel 4000 and nvidia 630m...

I installed bumblebee and intel drivers from their website. I thought the brightness problem will be solved by installing these drivers.

But, brightness works only for two steps: that is, dim, medium, high... But, it doesn't increase step wise. Can you please help me sort this problem?

I'm a newbie to ubuntu and this is my first trial. So, please give me a detailed guide... Thank you :)

EDIT: My model is HP DV6 7040tx. My Laptop Model