windows 7 - Wake timers don't wake computer from sleep mode

I'm got a custom built PC running 64 bit Windows 7 Ultimate. So far everything works great except for one thing: it will not wake up from sleep mode for a wake timer or scheduled task.

Sleep mode itself works great. If it's sleeping, it wakes successfully when I press the power button, mash the keyboard, wiggle the mouse, or send a WOL packet. The only problem is wake timers. I even tried the program WakeupOnStandBy but it looks like that uses wake timers, so it doesn't do anything for me either.

And yes, wake timers are enabled:

Any ideas on how to fix the problem, or troubleshoot it? I'd imagine that there would be a log somewhere telling me exactly why the wake timers are having trouble, but if there is I haven't found it.