ansel: command not found

Have You tried accessing the binary with the full path?

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/ansel - from package: php-horde-ansel

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