ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/C2H4N4O4/c3-1(4)2(5(7)8)6(9)10/h3-4H2/file?format=sdf&get3d=True  -- InChI=1S/C2H4N4O4/c3-1(4)2(5(7)8)6(9)10/h3-4H2 could not be loaded.