If you are unable to download an app due to geographic restriction, it's probably because the same email is registered at amazon.com and amazon.ca. You need to flip the country to the app store you want to download from.
Here is how:
1) Go to "Manage my Kindle" http://www.amazon.com/gp/digital/fiona/ ... footer_myk
2) Change country
Just did this in order to download tunein radio pro from amazon.ca. My kindle account was defaulting to the US. I needed to change it to Canada then I was able to download the app of the day from amazon.ca without an issue. Once completed, I went back into country setting and put it back to US.