I'm trying to use the Video Input FX to grab a freeze frame from an incoming video feed - but the option in the preferences to enable Video Input FX is greyed out.

System details:
2208 Mac Pro
Mac OS 10.6.8 and Catalyst 4.40_m329
I wonder if it's my graphics card - that's a NVIDEA GeForce 8800 GT

I have two LFG4 cards installed, and have Maximum Active Quicktime Outputs and Maximum LFG Digitisers set to 8.
The LFG Direct API is enabled at LFG Pal 768x288 - deinterlaced.

Any ideas anyone?

Thanks!
Tim