storeBackup_du: 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/storeBackup_du - from package: storebackup
/usr/share/storebackup/bin/storeBackup_du - from package: storebackup

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

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