Vector Blur......Missing Object when rendering

The vector blurring seems to not be working when rendering.

The compostor/Node editor will show the vector blur working the way it is suppose to.

When i render the scene it will just show the object not the blur, and in the dos window it says
Speed Table: Missing object droplet2

I am using the tutorial from blenderguru on the rain.

Any Suggestions?

I am having this exact issue with Blender 2.55 the official version from the Blender website.

I ran into similar compositing problems. I noticed they went away when I turned off certain environmental lighting. Try turning off all additional lighting in the world section.