mzscheme: 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/mzscheme - from package: racket

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

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