BackupPC_Admin: 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/share/BackupPC/sbin/BackupPC_Admin - from package: BackupPC

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

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