pamscale: 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/pamscale - from package: netpbm-progs

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

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