On many PCs if they are asleep then they do not wake because Windows is not running. So why would you expect it to wake up?
Let's do a little research. But I can't offer any suggestions because the make/model of this PC is unknown.
Again, waking from sleep is very dependent on the machine and if the person/company that made it got all the drivers right.
I am running Windows 7, Home Edition.
I monitor a webcam and my computer takes a picture once a minute. This process can last from 7 to 10 hours. ( For the curious I collect ships that [*** through the Port Phiiip heads in Victoria, Australia.)
When I set my timer for 8 hours and check on it in the morning, the computer is off as expected, and a glow is pulsing around the power button. When I press the power button, the computer comes to life but it does not boot from a cold start, but seems to be on standby..
When the unit went on standby it shut down the timer that I had set. and the program that was taking the pictures. As soon as I powered it up again the timer and the photo program took up where it left off when the unit went on standby.
The solution is to lengthen out the time for the computer to delay its standby sufficiently to allow my timer to shut the machine down.
Any help would be appreciated.