Mercedes Benz repair: 1988 mercedes car, mercedes car, key hole

Question
i have 1988 mercedes and am try to remove ignition i see that you turn cap ring to opposite side of key hole and line up holes . i have pushed the pin in but wont come out

Answer
Data needed:
Model.
Miles on the car.
Geographic location = nearest major city.

Answer:
This link should have all the data you need.

Ignition Cylinder Tumbler replacement; mixed diesel/gas
http://www.mercedesshop.com/shopforum/showthread.php?p=1065596