In time of import i've got message "Wrong URL/path used for attribute..." -Please add detailed description to debug to view full path with filename... -Same info about wrong URL nothing tells -you check filename like stupid guy everything exist, paste in webbrowser full path of file and the image is displayed... -and with full path with debug is easier to find where is problem.

In my case the problem was that i've put images on local fileserver and choose dropbox as source and there images isn't fetched locally ;(