registrationx: 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/lib/cmtk/bin/registrationx - from package: cmtk

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

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