How to add custom wallpaper

[FlyHotel]

Hey guy's

I'm trying to add custom wallpapers, i can see the wallpaper in the catalogue. But when i buy it and place it in the room, the wall turns white.
Screen; http://prntscr.com/35gtlh


Does someone knows how to add this correctly?

Thanks,

FlyHotel

[MentaL]