Well that is good if you are not seeing any light on that circle (which is supposed to be a sphere). You are only supposed to see some a sphere with some shading and light. If you are not then the problem should be with the code and I hope I can fix it. Can you try changing the place of the light by changing the array and see if it creates any difference? I assume it wont though...
our @Light_Position = ( 1.0, 1.0, 1.0, 1.0 );