ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI%3DInChI%26%2361%3B1S/C4H4/c1-3-4-2/h1%2C4H%2C2H2/file?format=sdf&get3d=True  -- InChI%3DInChI%26%2361%3B1S/C4H4/c1-3-4-2/h1%2C4H%2C2H2 could not be loaded.