ddtc: 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/ddtc - from package: ddtc

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

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