The pins within a lock are matched with the keys for a smooth operation. Thus, you might experience problems if you have lost your original key and are now operating the lock with a duplicate one. Any variation can cause a huge difference, therefore when duplicates are made, the key can become nonfunctional. Additionally, when duplicates are made from duplicates, the variation increases and the problem persists and prolongs. A better idea would be to get your lock rekeyed, and have the locksmith make as many keys as you need. Professionally-made keys are identical and do not vary in any manner.
Even if the door is installed and hung properly, careless installation of the strike will cause problems. Bolts and latches should be centered with their respective strikes. Additionally, the strike for the entry lock latch needs to be positioned so that the dead latch plunger does not fall in the strikes opening. The strikes should also be installed with screws long enough to anchor the strike into the framing behind the jamb. The screws should be at least 3 inches long.
Poorly mounted or lose hinges can cause a lot of problems. Three hinges with four screws are usually attached to a standard door jamb. When these hinges are not attached properly, it creates a problem. At least one screw attaching the hinge to the jamb should be of sufficient length.
If you fail to securely mount the hinges, the door will sag and will interfere with the alignment of the strikes and lock. Calling a locksmith for help in such a case is recommended. The first thing they will do is check the gap between the jamb and the door. This will help the locksmith to identify the problem and make the necessary repairs and adjustments.