it could be that your lock seized up from not using it at all..not necessarily seized...but try some wd40. just stick it in there (with the little straw that comes with it and give it a good squirt)...
the only other thing i could guess is that it's not the right lock for the key. which both you and me would hope not.
but i know what you mean about wiggling the key in order to get it to work. i hate that.
