Unexpected…

blocks.geo
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			// Gmsh project created on Wed Nov 27 11:24:05 2013
			h1=0.7;
			h2=0.45;
			s = 2;
			Point(1) = {-2*s, 0, 0, h1};
			Point(2) = {2*s, 0, 0, h1};
			Point(3) = {2*s, 2, 0, h1};
			Point(4) = {-2*s, 2, 0, h1};
			Point(5) = {-1*s, 2, 0, h2};
			Point(6) = {1*s, 2, 0, h2};
			Point(7) = {1*s, 3, 0, h2};
			Point(8) = {-1*s, 3, 0, h2};
			Line(1) = {1, 2};
			Line(2) = {2, 3};
			Line(3) = {3, 4};
			Line(4) = {4, 1};
			Line Loop(7) = {2, 3, 4, 1};
			Plane Surface(8) = {7};
			Line(9) = {5, 6};
			Line(10) = {6, 7};
			Line(11) = {7, 8};
			Line(12) = {8, 5};
			Line Loop(13) = {9, 10, 11, 12};
			Plane Surface(14) = {13};
			Physical Line("bottom") = {1};
			Physical Line("top") = {11};
			Physical Line("interface_bottom") = {3};
			Physical Line("interface_top") = {9};
			Physical Surface("Bottom_body") = {8};
			Physical Surface("Top_body") = {14};