darkproducer: 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 CentOS possible default full paths are:

/usr/sbin/darkproducer - from package: darkserver-importer

You may install the required package with command yum install {package}

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