If it is solid behind the holes then the key may not be at the number 2 position. Look in your owners manual, I believe it shows the positions.

Are you able to turn the key clockwise past the 1 position? This is the first step. If so do NOT turn the key back to the original position as was previously stated.

You should be able to see the holes.

Look at the thread "Help! Newbie has Tumbler problem". In figure 21.6 it shows the tumbler/barrel. You can see the hole and the slot/hole running through the tumbler. You can also see a little black tab between his thumb and index finger. This black tab is what you are trying to push down with the pin/wire you insert in the hole. Push this tab in and the tumbler comes out.

Not sure if you have a screw off black collar or if it just pops off when you release the tumbler as was the case on my E320. Any 190 owners know?