Key Problem

i recently lost my keys to my car and do not have a spare set. I called a nissan dealership and had a new key made for my '93 Altima by giving them the VIN # and they looked up the keycode. The problem is that I was using two different keys before this, one for the doors and one for the ignition and there is only supposed to be one key to do both. I retrieved this key from the dealership and it only opened my door, it fit into the ignition but would not turn. I tried it multiple times but it would not work. Could someone have changed the ignition lock so that the keycode in the registry for my car is no longer valid? Also, do I have any options to get a key that would work for my ignition or being able to drive the car without the key.