Le Verrier may have been wrong about Vulcan, but he is credited with the discovery of Neptune. He calculated the location of a planet beyond Uranus, sent the information to an astronomer, Johann Galle, at an observatory in Berlin, and Galle found Neptune within an hour within one degree of where Le Verrier predicted it would be. That was in 1846 and Neptune takes 164.8 years to go around the sun once, so it is now very close to where it was when it was discovered.
Based on the Vulcan episode. I would expect modern scientists to be more careful in predicting new planets - so this could prove to be true.-Tom