Is this possible that I made 31post and non of the post require to be awarded a merit.
Yes, you can make as many posts without much effort and get no merit.
I think instead of counting post they should always count a merited post. This will make one know that once your post is counted you equally have merit.
So a situation where merits validate a post? I do not see the purpose of that, as merits, posts and activities are counted distinctly and you'll be notified once you get a merit.