ndtpcheck: 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/sbin/ndtpcheck - from package: ndtpd

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

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