Cannot open display:

Usage: pcmanfm [OPTION?] [FILE1, FILE2,...] Help Options: -h, --help Show help options --help-all Show all help options --help-gtk Show GTK+ Options Application Options: -p, --profile=PROFILE Name of configuration profile -d, --daemon-mode Run PCManFM as a daemon --no-desktop No function. Just to be compatible with nautilus --desktop Launch desktop manager --desktop-off Turn off desktop manager if it's running --desktop-pref Open desktop preference dialog --one-screen Use --desktop option only for one screen -w, --set-wallpaper=FILE Set desktop wallpaper from image FILE --wallpaper-mode=MODE Set mode of desktop wallpaper. MODE=(color|stretch|fit|crop|center|tile|screen) --show-pref=N Open Preferences dialog on the page N -n, --new-win Open new window -f, --find-files Open a Find Files window --role=ROLE Window role for usage by window manager --display=DISPLAY X display to use