ossmix: 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/ossmix - from package: oss4-base

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

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