need help on 1st level

[inkman]

OK,

Ive completed all assigned things to do on the 1st level and I'm now at the vault door and cannot get in. I have found all the things to go through, even some keys. but how do I get through the vault door in the basement?

[Astalder]

Hint #1
There's another region connected to the one the vault is in.

Hint #2
You read in a note earlier that there's a switch in the owner's room, that room is in this additional region.

Hint #3
His room is on the second floor.