95 Olds turn signal/brake light problem

[js_specials]

95 Olds Cutlass Supreme, 3.1 L V6 with cruise controls located on the turn signal stem.

If I put either turn signals on, my turn signals work properly.
If I put my left turn signal on and hit the brakes, my rear brake lights, with the exception of the middle light, go out. The middle light operates properly.
If I put my right turn signal on and hit the brakes, all of my brake lights work properly.
If I turn my lights on, and use either turn signal and hit the brakes, everything works properly.

Any idea what the problem may be?