mkc_check_custom: 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/mkc_check_custom - from package: mk-configure

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

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