Alexa Rank problem.

Hi I have a website with a traffic, Google analytics shows that I have a 1.3 million visits / day and 580K unique visitors / day. when I get to alexa, I sow my website as a 4000 / world rank, The problem isn't the world traffic rank it's pretty good but my competitors websites in my country, their users are less from mine, they have a 350K unique visitors / day.. but they are for example 22 rankd in my country but I 79.. Any suggestions or help? Thnaks