Hi, I think its not on the number of post but the quality of the post you make. In local forums they start deleting zero value posts and posts that is not related to Bitcoin. You can check the the Newbies read before posting. Maybe some of your post were deleted or not counted. Quality over quantity. Good luck to us. 
If any of my posts were deleted, so it would be shown less number of made posts in my profile. And the quality of posts is good. I usually post in Bitcoin discussion, Altcoin discussion, Economy and Services threads. And the posts are not short.He has been on the site (and posted ) for more periods then you have been, which means he could potentially have/get more activity, which is indeed the case.
Code:
time = number of two-week periods in which you've posted since your registration
activity = min(time * 14, posts)
activity = min(time * 14, posts)
Your time=~3 (October - november)
While his time ( from october - december/november) would be ~6?
You can get ~1 activity per day, and it gets updated every 14 days.
If you post once in the 14 days, you will still get the potential activity added to your account.
Thank you, mate! You have cleared the situation for me. So all I need to do is to keep posting on a permanent basis and my rank is going to update every 14 days?