dhcpy6d: 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/dhcpy6d - from package: dhcpy6d

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

Error in other languages:
dhcpy6d: bevel nie gevind nie
dhcpy6d: comandă negăsită
dhcpy6d: comando não encontrado
dhcpy6d: commande introuvable
dhcpy6d: command not found
dhcpy6d: käsku ei ole
dhcpy6d: không tìm thấy lệnh
dhcpy6d: komanda nerasta
dhcpy6d: Kommando nicht gefunden.
dhcpy6d: kommandot finns inte
dhcpy6d: komut yok
dhcpy6d: nie znaleziono polecenia
dhcpy6d: níor aimsíodh an t-ordú
dhcpy6d: no se encontró la orden
dhcpy6d: no s'ha trobat l'ordre
dhcpy6d: opdracht niet gevonden
dhcpy6d: parancs nem található
dhcpy6d: perintah tidak ditemukan
dhcpy6d: príkaz nenájdený
dhcpy6d: příkaz nenalezen
dhcpy6d: команда не найдена
dhcpy6d: командата не е открита
dhcpy6d: 命令找不到
dhcpy6d: コマンドが見つかりません