mkdarts: 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/mkdarts - from package: darts

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

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