wmix: 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/wmix - from package: wmix

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

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