I post an ad message in one of the Yahoo groups, but never appears, why?

Can anybody explain how come a message I post in Yahoo groups never appear in the group's message board? I am already a member of the group in which I post my message and the group doesn't need any moderator's approval. How to make my message appear? As I finish writing my message I click the "post" on and a message saying "Your message has been posted" appear but when I look for my message in the list, it just not there. What have I done wrong?