Mac Pro (early 2008) won't sleep by itself since Lion upgrade

[doc4x5]

I've searched the fora, restarted many times, turned file sharing off, and still my Mac Pro 2008 will not go to sleep by itself. It will sleep with the command on the Apple menu. There are no problems awakening it with a key or mouse touch. Prior to the Lion upgrade, it seemed to have no problem. I'm trying to be an energy saving good guy. It has 6GB RAM, and four drives in the bays, nothing exotic is attached to it, just couple of printers, both of which are usually off. Any thoughts would be appreciated.
Thanks.
Eric

 

[GGJstudios]

You may find some useful ideas here. Perhaps there's something you missed:

Mac OS X: Why your Mac might not sleep or stay in sleep mode
Determine why your Mac wakes up from sleep
One sleep problem caused by printers - solved ... and another