Sample-NiSimpleViewer: 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/Sample-NiSimpleViewer - from package: openni-utils

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

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