cassiopee: 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/cassiopee - from package: cassiopee

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

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