Hmmm....I Had that problem but it was on the camera configuration...

Verify that the camera u r using (persp,top, etc or camera1 if u created one) is renderable go to the attribute editor of the camera and i think is on the output setting (i dont have maya right now in my pc so im trying to remmeber the main option) check the RENDER check box

and if you are using render layers verify that you have the layer that has the paint effect has beauty on and render on

Just throwing some ideas....

hth