pkttyagent: 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/pkttyagent - from package: policykit-1

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

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