Problem with Traffic

Hi,
I have a site whose PR is 3 and none of my competitors have PR more than 2 but my site traffic is too low than them. I have checked the SERP ranking too and I am almost on top on most of keywords. What is the problem. Can anyone tell me?
Can anyone please analyze my and my competitor site ?

you might be on the first page for a lot of keywords but if no one actually search using these keywords you won't see any traffic

check the exact monthly searches for your keywords