kbanner.kss: 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/kbanner.kss - from package: kscreensaver

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

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