Thunderbolt Display: FireWire not working

Hi everyone

I have a Thunderbolt Display connected to my MacBook Pro.

Everything works fine, except the FireWire Port on the Display: When I plug in a device nothing happens. I tried several FW Harddiscs without success. They don't even seem to get any power to spin up, simply no reaction.

Any ideas what the problem might be?

Thanks in advance!

Tech Specs:

MacBook Pro Retina, Mid 2012

- OSX 10.8.5

- 2.6GHz Intel i7

- 16GB RAM

- NVIDIA GeForce GT 650M 1024MB

- Thunderbolt Firmware 23.4

Thunderbolt Display 27"

- 2560x1440 Px

- Firmware Version 22.2