Ubuntu Multimedia :: How To Get Banshee Sleep Timer Plugin To Work

I have Banshee's alarm plugin installed. From Banshee's menu, I click on Tools → Alarm Clock → Sleep Timer. The timer looks like it should be set according to 24-hour time, so I set it for 2 minutes past the current time and click "Okay". The timer doesn't turn off the music when the designated time comes and goes. Thinking that maybe it's a countdown timer, I just set the thing to 2 minutes, but 2 minutes later the music keeps playing on and on. I go Tools → Alarm Clock → Alarm and put a check mark in "Enable Alarm" and try the sleep timer again, but still it doesn't work. I'm running 10.04 64-bit.