probabel: 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/probabel - from package: probabel

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

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