mixvm: 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/mixvm - from package: mdk

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

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