SceneViewer: 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/SceneViewer - from package: inventor-clients

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

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