Mercedes: trunk lock 260e, mb2, master key

Question
My trunk wont open! All automatic locks sound like they are engaging and the master key turns the tumblers in the cylinder but pushing in the button I get no click. Any suggestions?

Answer
This is all the data I have:

http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=124026%5F501&M=103%2E940&GA=722%2E40...

Trunk lock problem-W126 300SD
http://www.mercedesshop.com/shopforum/showthread.php?p=879700#post879700

trunk won't open
http://www.mercedesshop.com/shopforum/showthread.php?p=512820#post512820

82 300SD Trunk Won't Open
http://www.mercedesshop.com/shopforum/showthread.php?t=15438