WakeOnLan Sleep function not working

I have setup an old PowerMac G4 running 10.4 as a music server for all my devices running iTunes, and it's now working great. I have installed WakeOnLan to wake the server before using iTunes on my macs, and iNet WOL on my iPod Touch for the same purpose. When I am done using iTunes I'd like to be able to put the server to sleep. iNet WOL does that perfectly from my iPod, but for some reason the Sleep function in WakeOnLan running on My MacBook Pro w/10.6 does nothing. Any clues? TIA.