rgbcorrelator: 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 Debian possible default full paths are:

/usr/bin/rgbcorrelator - from package: pymca

You may install the required package with command apt-get install {package}

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