But it's also possible that it's right where it should be and is too faint to be detected. Asteroids are very hard to detect because they're faint and they move -- so you can't expose the image for a long time to detect a fainter image. All you would get would be a faint streak across the image.
The other reason this is difficult to do is because it's hard to guide the telescope. The bright guide stars you're using to correct for the small motions the telescope is making due to wind, etc. are now moving in your field of view and can't be used to guide the telescope.
Finally, you have to know the trajectory pretty well to do this. You have to not only know how fast to move the telescope, but the right direction to move the telescope. This can be done for a well studied object where the uncertainty in the trajectory is pretty small. But if the object hasn't been observed for 14 years, you probably won't have very good knowledge of its trajectory.