96 Jetta Power Locks

The power locks on my 96 Jetta quit working recently and I do not know why. When I turn the key in the door to unlock it, there is a sound like it is trying to unlock all the doors (For about 3 minutes or so), but only the driver's door unlocks.

I took it to the mechanic to check the vacuum advance, but he said it had good suction. I cannot figure out what would make them not all work. Does anyone have any ideas that do not include the vacuum advance?

My '95 does the same thing. Its due to a leak in one of the vacuum lines from the pump/reservoir to the locks. Mine leak was on the line leading to the trunk lock, where the hose is exposed on the right side of the trunk lid.