XnSensorServer: 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 CentOS possible default full paths are:

/usr/bin/XnSensorServer - from package: openni-primesense

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

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