I am currently managing the Ottawa 67's and I according to the GM rankings I am 2nd in the CHL. I have applied for the Canada and the US under 20's team for the WJC the last two years and haven't gotten it. Is there any secret to getting it, or do I just need to keep trying?

Just keep trying. Winning a few OHL championships will help.

Also, it does seem to depend on what nationality you give yourself when you create the game. As an American GM, I'm almost NEVER offered a Canadian national team job, even the under 20s. I think I've gotten Team Canada once in either division.