[ PovRay ] default with merge !?!...

Hi all,

Do you know how I can avoid this default with the intersection of both 
object?
Bruno
--------------------------------------------------------------------------------


#version 3.6;

#include "colors.inc"

global_settings {
	assumed_gamma 1.0
}

// ----------------------------------------

camera	{
    	location <10, 15, -15>
    	look_at <6, 4, 0>
}

sky_sphere {
	pigment {
		gradient y
		color_map {
		[0.0 rgb <0.6,0.7,1.0>]
		[0.7 rgb <0.0,0.1,0.8>]
		}
	}
}

light_source { <-30, 30, -30> color rgb <1, 1, 1> }

// ----------------------------------------

plane { y, 0 pigment { color rgb <0.7,0.5,0.3> } }

merge	{
	box { <0,0,0>, <3, 10, 8>
		matrix <  1,    0,  0,
	                  0.35, 1,  0,
	                  0,    0,  1,
	                  0,  0,  0 >	
	}
	box { <0,0,0>, <3, 10, 8>
		matrix <  1,    0,  0,
	                 -0.35, 1,  0,
	                  0,    0,  1,
	                  8,  0,  0 >	
	}
	pigment { rgbf< 1, 1, 1, 0.6>}

}