calibrate_lens_gui: 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/calibrate_lens_gui - from package: hugin

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

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