Game won't give me my last location for Alaska

[clafitte]

I have 1 more landmark location left to finish that and get my achievement. However it will not acknowledge it on the game!? I have gone thru all 5 landmarks over and over and it won't show the fifth one. I have followed Mr. Arrow's video over and over too. On foot and on the 4-wheeler and it won't show it. It is the first one on the video. Any ideas??