WMP troubles with controls.previous() & controls.next()

Question

I'm creating a Windows Media Player skin and have ran into a road block. I can load a song fine, but my code (see below) for the next and previous features are not working. I'm wondering if there is something in the windows API to handle this feature? Do I need to use directory info or something? Any comments would be helpful-- Thanks

function OpenMedia() { newFile = theme.openDialog('FILE_OPEN', 'FILES_ALLMEDIA'); if (newFile) { player.URL = newFile; player.controls.play(); } }

function Previous() { if (player.controls.isAvailable('Previous')){ player.controls.previous(); } }

function Next() { if (player.controls.isAvailable('Next')){ player.controls.next();

}

}