I didn't see your reply until today. i was expecting a notification mail when a reply has been posted, you guys don't have auto generated notifications for this?
Okay back to the discussion. Interestingly i tested this Edge mapping in a simple scene and the results came out just fine without any problem. You can find the render and setups i have used in the attachment.
Am assuming it has something to do with render setup or the scene which am working on.
So i found out that the spline which i used and the surface was overlapping a little also i had to 'Disable' surface area in the Areas roll-out for it to work properly.