Can't sleep, powercfg reports driver blocking system is "?"

I'm having some issues with trying to send my computer into suspend. I've done quite a bit of research and know how I should be able to resolve it, but when I run powercfg -requests I get the following output:

Code:

DISPLAY:
None.

SYSTEM:
[DRIVER] ?
[DRIVER] ?
[DRIVER] ?
[DRIVER] ?
[DRIVER] ?

AWAYMODE:
None.

I've shut down every running process with no success in blocking the offender. I have no devices in my device manager that report having a problem with them. Any ideas on what I can do to fix this or find out what the ? is referring to?

Thanks.

It should be: POWERCFG.EXE -REQUESTS

Yes, that is the command I'm using. Fortunately it seems to be occasionally sleeping despite these unknown drivers being there to block it, but it's not sleeping as quickly as it is supposed to based upon the current power scheme.

Still can't figure out what these ?'s are.

Have you looked in Device Manager to see if there are any errors ?

Try this to see what is keeping it "awake"
For a more detailed analysis type: powercfg -energy -output %USERPROFILE%\Desktop\Energy_Report.html (which will icon on desktop). There will some "false" positives, but you will see the most likely culprit.