gkbd-keyboard-display: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/gkbd-keyboard-display - from package: gkbd-capplet

You may install the required package with command apt-get install {package}

Error in other languages:
gkbd-keyboard-display: bevel nie gevind nie
gkbd-keyboard-display: comandă negăsită
gkbd-keyboard-display: comando não encontrado
gkbd-keyboard-display: commande introuvable
gkbd-keyboard-display: command not found
gkbd-keyboard-display: käsku ei ole
gkbd-keyboard-display: không tìm thấy lệnh
gkbd-keyboard-display: komanda nerasta
gkbd-keyboard-display: Kommando nicht gefunden.
gkbd-keyboard-display: kommandot finns inte
gkbd-keyboard-display: komut yok
gkbd-keyboard-display: nie znaleziono polecenia
gkbd-keyboard-display: níor aimsíodh an t-ordú
gkbd-keyboard-display: no se encontró la orden
gkbd-keyboard-display: no s'ha trobat l'ordre
gkbd-keyboard-display: opdracht niet gevonden
gkbd-keyboard-display: parancs nem található
gkbd-keyboard-display: perintah tidak ditemukan
gkbd-keyboard-display: príkaz nenájdený
gkbd-keyboard-display: příkaz nenalezen
gkbd-keyboard-display: команда не найдена
gkbd-keyboard-display: командата не е открита
gkbd-keyboard-display: 命令找不到
gkbd-keyboard-display: コマンドが見つかりません