darkbuildqueue: 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/darkbuildqueue - from package: darkserver-importer

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

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