Look in the BIOS and see if wake by USB is enabled. It wasn't on my board. Also look in Device Manager and make sure the box for allowing this device to wake the computer is checked in the properties of the keyboard.
Yeah I checked the Bios and it didn't have that option but I think I solved it:
I bought a new wireless mouse and I connected it, it worked! Touch my keyboard and able to wake it from sleep mode.
Also realize that on my keyboard, the f6 key turns on sleep mode access for the key board -- so hold down Fn + F6 key and you'll see a bright dot appear once it's on. To turn it off, do the same thing.