Hello,
I landed at Coutts on December,2013.
I did use that same address in my GPS. That address will take you to a residential area, I think the postal code is responsible for that. However, the actual border is not that far. All you have to do is follow residential road along the high way, you would be able to see the high way on your left, but you, yourself will be in a small road right next to it. Drive for 45 seconds and you will be able to see a large building just around the right hand corner and you will know that you have arrived at your destination.
Thanks