Right Blinker not turning on

On my wife's car the right blinker is not working.
*I have checked and replaced all light bulbs.
*I have checked and replaced fuse.
*All lights in the rear right side light up when car lights are turned on.
*When I turn on the right blinker, only one of the two bulbs light up (mind you it lights up when the headlights are turned on.
*The one that lights up (Left inside bulb of the two) stays solid and does not blink.
*When I turn on emergency flashers the right side does not blink.
My wife states that after a minute or two she will sometimes get a slow blink when she turns on the right blinker.