Sunroof problem

Hi,

I have a 1999 Jetta Wolksburg edition. My sunroof is electronical, goes two ways: opens up all the way, or the back side of the sunroof tips out. The "tip-out" part is working, but I can't open it the other way. It starts, but it doesn't slide into the roof. As I press the button, I hear clicking, but nothing else. Anybody has any suggestions? Is there something stuck or the motor broke?

Thanks!