dtestx: command not found

Have You tried accessing the binary with the full path?

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/dtestx - from package: dapl-utils

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

On Debian possible default full paths are:

/usr/bin/dtestx - from package: dapl2-utils

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