mkelf-menu: 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

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/mkelf-menu - from package: mknbi

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