Well I'm a little taken aback that it didn't work. The next thing I'd recommend is doing a SMC reset, that might do it. If you have never done one it's pretty simple. Here is the advice letter and instructions:
http://support.apple.com/kb/HT3964
_iMac SMC RESET_
• Shut down the computer.
• Unplug the computer's power cord.
• Press and hold the power button for 5 seconds.
• Release the power button.
• Attach the computers power cable.
• Press the power button to turn on the computer.
Let's see if that does it.