ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI%3DInChI%3D1S/C2H2N4/c1-3-5-2-6-4-1/h1-2H/file?format=sdf&get3d=True  -- InChI%3DInChI%3D1S/C2H2N4/c1-3-5-2-6-4-1/h1-2H could not be loaded.