hello guy's - smooth shade issue

Hi Rachid,

You are not the first person to run into this.

There are a few ways to fix this; lowering the Angle in the Smooth By Angle Modifier, 'deepening the insets around the buttons, or Shade the top Faces Flat.

Have a look at some of the other posts, like this one: https://cgcookie.com/community/20931-triangles-on-surfaces-after-auto-smooth 

One of the main ones that tend to help is cutting the Ngon smaller on that main face, so connecting from vertex to vertex with J to make a cut. Also checking your faces are totally straight on the Z axis, so selecting all the faces and S then Z then 0.