ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI%3DInChI%3D1S/C4H6O2.C2H4/c1-2-3-4%285%296%3B1-2/h2H%2C1%2C3H2%2C%28H%2C5%2C6%29%3B1-2H2/file?format=sdf&get3d=True  -- InChI%3DInChI%3D1S/C4H6O2.C2H4/c1-2-3-4%285%296%3B1-2/h2H%2C1%2C3H2%2C%28H%2C5%2C6%29%3B1-2H2 could not be loaded.