Sample-NiHandTracker: 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-NiHandTracker - from package: openni-utils

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

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