external fx in cubase 6.07


I want to install the tc finalizer as an external fx in cubase 6.07
I conncted the spdif out of my focusrite saffire pro40 external firewire interface to the input of the finalizer and the output of the finalizer to the spdif input of the pro40. I get a signal into the pro40 but only when I set the control panel daw to spdif and I only get a digital sweeping noise in return. I set up cubase external fx in the vst control menu then I got no sound at all. Can you please assist me?