Many thanks to receive your reply about the technical of Vray. And here my example skp with HDRI for background.
Before I use to finish my product with background in PS, but when I see the products of my friend with HDRI (of course they don't use Sketchup), it look really realistic, and it make me effort to use HDRI background with Sketchup and Vray version. But I have a trouble as I said.
The tutorial I try to do with "VRayForSketchUp_01.00.74" version.
And here the HDRI after convert to JPG
And here the trouble of mine after render: