Alienware 17 TactX macro keys help

Hello,

So, I got this new AW17. It has 4 kinda useless macro keys above the num pad, and I couldn't really figure out what to use them for.

Then i remembered, one thing I really dislike is having to use two keys to adjust the volume and the screen brightness, and since there was 4 keys there, it just fits as well.

So, I get into the TactX software, i change the C and D to Volume down/up, and it works beautifully. Then I try to turn A and B into screen brightness down/up, but it won't register anything.

Any idea what is wrong?