1. Dont put a breakable object textured with nodraw. If you want an invisible breaking object, make the object ANY texture you want, open the properties, switch the texture mode field to 'texture', and then make the render amount '0'.
2. Make sure ALL of the sides of that func_breakable are textured with the brick wall texture.
3. Wierd? Change the lights around those black areas into light_dynamics and see if it does it right.