When I send an Im in yahoo the conversation area does not show me sent message or message recd .?

While using yahoo messenger for IMs I type the text in text window and send .The message sent is not shown in the conversation area of the window and also the message recd is also not shown in the conversation area of the window .Why?What settings r to b done I have already uninstalled the Yahoo an reinstalled the new version .But same result.Why? what settings r required to b done?