I have a bunch of boxes flying apart in Cycles, and I'm using the Vector Blur node for motion blur. Nothing's blurring.
It's the simplest compositor setup: RenderLayer Image/Z/Speed goes to Vector Blur node Image/Z/Speed, Vector Blur node goes to Comp.Out and Viewer.Out. I've tried all sorts of settings on the VB node, but nothing changes. What have I not set up?