vstream-client: 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/vstream-client - from package: vstream-client

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

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