Power trunk problem

The power trunk on my 1999 Jetta GLS has stopped working. If I use the key I can hear the power motor run but the lock does not disengage. The same thing happens if I use the power trunk switch on the drivers door. The key worked sometimes but now not at all. Any ideas where to start looking?

Thanks

Does noboby have any idea what the problem is?

If all the other doors lock/unlock properly, then concentrate on following the vacuum hoses in the trunk area.

After folding down my back seats and crawling into the trunk from the inside of the car I managed to open the trunk by manually turning the latch. Upon inspecting the latch I noticed the cable that unlocks the latch was broken. Thats why I could here the motor but the trunk would not open. I re- attached the cable and the power trunk works perfectly.