lp-milestone2ical: 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/lp-milestone2ical - from package: lptools

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

Error in other languages:
lp-milestone2ical: bevel nie gevind nie
lp-milestone2ical: comandă negăsită
lp-milestone2ical: comando não encontrado
lp-milestone2ical: commande introuvable
lp-milestone2ical: command not found
lp-milestone2ical: käsku ei ole
lp-milestone2ical: không tìm thấy lệnh
lp-milestone2ical: komanda nerasta
lp-milestone2ical: Kommando nicht gefunden.
lp-milestone2ical: kommandot finns inte
lp-milestone2ical: komut yok
lp-milestone2ical: nie znaleziono polecenia
lp-milestone2ical: níor aimsíodh an t-ordú
lp-milestone2ical: no se encontró la orden
lp-milestone2ical: no s'ha trobat l'ordre
lp-milestone2ical: opdracht niet gevonden
lp-milestone2ical: parancs nem található
lp-milestone2ical: perintah tidak ditemukan
lp-milestone2ical: príkaz nenájdený
lp-milestone2ical: příkaz nenalezen
lp-milestone2ical: команда не найдена
lp-milestone2ical: командата не е открита
lp-milestone2ical: 命令找不到
lp-milestone2ical: コマンドが見つかりません