ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/C2H4N4O2/c3-6-1(7)4-5-2(6)8/h3H2,(H,4,7)(H,5,8)/file?format=sdf&get3d=True  -- InChI=1S/C2H4N4O2/c3-6-1(7)4-5-2(6)8/h3H2,(H,4,7)(H,5,8) could not be loaded.