Hi Tasha,
I moved your post from the walkthrough thread and created a new topic for you.
Are you making sure to turn the dial left-right-left, etc? Did you try clicking on the handle of the safe after moving the dial to the final number, even though you didn't hear anything?
MaG's walkthrough states:
Sound need not be heard when numbers are placed under the red dot. In my game, I didn't hear a sound when the correct numbers are under the red dot.Since the numbers are random you could try going back to a previous save game and replaying through, and see if you get a different set of numbers to try.

If you still have problems please let us know!