mixasm: 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/mixasm - from package: mdk

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

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