The backstory: There is legislation called the “Canada Heritage Act”—although it isn’t consistently applied across all books (some types of books, e.g., textbooks, books without pictures, etc. get treated differently than others) the long and short of it is that it basically prohibits The Wood Database from shipping books to Canada through Amazon.com. 

Potential workarounds: Use a package holding/forwarding service like Kinek or Borderlinx.