I'm not entirely sure what you have done either
, but if I were you I would start the texture loading process again as something has gone funny.
I would remove the CStone-Bucks County CSV-368183.jpg in the library manager by selecting it and clicking the remove button at the bottom. This won't delete the file, just stops it from being loaded (from the wrong location, which is probably why the original message occurred.)
Put the image in a folder where you can keep all your custom textures, preferably on the server. Go back to the Library Manager and click the Local/Lan tab at the top. Locate and select the
folder
you have put the jpg in, and click 'Add' at the bottom. Now click Done when you are finished.
In the material setup, check the cut stone material is looking for the right named jpg. If not, locate it using the search button, size it correctly, and press the 'Match with internal Engine' button again. Hopefully all should be working properly again with no error messages!