Thank you for your answer but I never say I tell LaunchBox that the image are on C, I think it's not possible, all images are directly in the Launchbox directory, paths are relatives
I said : I first install on the network drive and everything work except the Box Art, however they are present as you ca see on the screenshot when I go on the Edit rom section.
And when I move the directory on C: drive it's working with no change, when I move the directory everywhere (on c: , on d: ... ect) it's working except on network drive (Letter Z) I don't understand why, si I ask here.
Sorry if my English is not very good, I'm french.