Hasta La Motion!

hi i am trying to create a kernal defocus node. i used to use it before but no longer have access to it, so im trying to recreate it. so far i have a convolve node with the A pipe plugged into a constant that is 32 x 32 px with a circular matte inside it then i have a transform node after that. pipe B is connected to the image i want to defocus. to animate the kernal defocus i increase the scale in the transform node. is there anything else that i am missing or can me added. here is a screen shot of my script.

http://www.flickr.com/photos/49663121@N04/5387371826/