dtn2admin: 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/dtn2admin - from package: ion

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

Error in other languages:
dtn2admin: bevel nie gevind nie
dtn2admin: comandă negăsită
dtn2admin: comando não encontrado
dtn2admin: commande introuvable
dtn2admin: command not found
dtn2admin: käsku ei ole
dtn2admin: không tìm thấy lệnh
dtn2admin: komanda nerasta
dtn2admin: Kommando nicht gefunden.
dtn2admin: kommandot finns inte
dtn2admin: komut yok
dtn2admin: nie znaleziono polecenia
dtn2admin: níor aimsíodh an t-ordú
dtn2admin: no se encontró la orden
dtn2admin: no s'ha trobat l'ordre
dtn2admin: opdracht niet gevonden
dtn2admin: parancs nem található
dtn2admin: perintah tidak ditemukan
dtn2admin: príkaz nenájdený
dtn2admin: příkaz nenalezen
dtn2admin: команда не найдена
dtn2admin: командата не е открита
dtn2admin: 命令找不到
dtn2admin: コマンドが見つかりません