Recently purchased a Sunline 2003 and it only had one key for the door, I got other keys made for the compartments but am having trouble finding someone to make me a spare key or two for the main door. The key that I have now has black rubber on the back and I don't know if that is why no one can make me one or not. Do I need to go to a RV dealer? I tried Lowes and Home Depot. Thanks for any advice.