zita-at1: 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/zita-at1 - from package: zita-at1

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

Error in other languages:
zita-at1: bevel nie gevind nie
zita-at1: comandă negăsită
zita-at1: comando não encontrado
zita-at1: commande introuvable
zita-at1: command not found
zita-at1: käsku ei ole
zita-at1: không tìm thấy lệnh
zita-at1: komanda nerasta
zita-at1: Kommando nicht gefunden.
zita-at1: kommandot finns inte
zita-at1: komut yok
zita-at1: nie znaleziono polecenia
zita-at1: níor aimsíodh an t-ordú
zita-at1: no se encontró la orden
zita-at1: no s'ha trobat l'ordre
zita-at1: opdracht niet gevonden
zita-at1: parancs nem található
zita-at1: perintah tidak ditemukan
zita-at1: príkaz nenájdený
zita-at1: příkaz nenalezen
zita-at1: команда не найдена
zita-at1: командата не е открита
zita-at1: 命令找不到
zita-at1: コマンドが見つかりません