suroof leak from rear passengers side
 

I have a 2000 A6. I have had a rear passengers side leak from my sunroof. I noticed that my trunk was getting wet. I tracked the leak down to the right rear sunroof drain. The preplexing thing is that it looks like the rail on the suroof is leaking befoe the white box that the green drain hose attaches to. I have no idea of how to diagnose &/or fix the problem.

anyody know how to fix such a problem???