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I was new to StackOverflow. All I did was ask a question as other newbies. My reputation deteriorated to "3" and I was unable to post questions anymore.
After reading all the FAQ I realized the concept of StackOverflow.
So, I reviewed all my question/answers, also answered others' questions and gained a reputation of "22". I'm now able to chat. But still, I cannot "Ask Question" on StackOverflow.