Intensity Shuttle Thunderbolt isn't recognized

My iMac 12,1 mid 2011 won't recognize the Intensity Shuttle Thunderbolt. In the system preferences, in the blackmagic panel everything is greyed. I have installed the drivers that came inside the box. The same Intensity Shuttle Thunderbolt with the same cable works on my matchbook pro 13". I have Lion 10.7.4. But the weird thing is that the device work Ok on some systems and others don't work at all (the lights inside the shuttle are off). It seems that there isn't electrical current in the shuttle. I already update my efi firmware, clean the system, etc...What's the problem... please help.

[Sarah Jones]

Do you have another Thunderbolt device you can test with the Thunderbolt port on the iMac that does not seem to be powering up the Intensity Shuttle? Ideally we'd like to rule out if the issue only follows the Intensity or if there is a larger problem at the system level.

Despite not showing up in System Preferences, in your System Information under Thunderbolt -> Port: Status: do you see anything connected there?

You may also want to visit our website to download the latest drivers as what came in the box may potentially be a bit older.

If you require more in depth assistance, you are also welcome to contact your nearest Support office directly to speak with someone. You can find this contact information via our website here: http://www.blackmagicdesign.com/company/