dfbtest_scale: 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/bin/dfbtest_scale - from package: directfb

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

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