mlnet: 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/mlnet - from package: mldonkey-server

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

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