gadmin-proftpd: 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/lib/debug/usr/sbin/gadmin-proftpd - from package: gadmin-proftpd-dbg
/usr/sbin/gadmin-proftpd - from package: gadmin-proftpd

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