Oh Sahar plz don't feel bad.
The reason behind our forum's rank decrease is that we had no IF article . Buzz articles gave many other forums higher points although their activity is lesser than ours.
We have very less number of members in comparison with other forums..yet we manage to be in no.12 in activity. I agree we could be more active , but this won't make a big change in ranking..coz buzz articles, and number of members count more than activity.