Clear playlists and play another file

Hi.

I'm using MOC 2.4.4, and it's my favorite MP3 player. But there's something that I really don't like:

When I add files to the playlist, the songs play normal. But, if I stop the player (key s), clear the playlist (key C), and add other files, Moc play only the first song of the new songs. Then it plays the older songs (those that I cleared from playlist before), and not the newer songs (that appear correctly on playlist). What am I doing wrong?