camlp5sch: command not found

Have You tried accessing the binary with the full path?

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/camlp5sch - from package: camlp5

You may install the required package with command apt-get install {package}
Error in other languages:
camlp5sch: bevel nie gevind nie
camlp5sch: comandă negăsită
camlp5sch: comando não encontrado
camlp5sch: commande introuvable
camlp5sch: command not found
camlp5sch: käsku ei ole
camlp5sch: không tìm thấy lệnh
camlp5sch: komanda nerasta
camlp5sch: Kommando nicht gefunden.
camlp5sch: kommandot finns inte
camlp5sch: komut yok
camlp5sch: nie znaleziono polecenia
camlp5sch: níor aimsíodh an t-ordú
camlp5sch: no se encontró la orden
camlp5sch: no s'ha trobat l'ordre
camlp5sch: opdracht niet gevonden
camlp5sch: parancs nem található
camlp5sch: perintah tidak ditemukan
camlp5sch: príkaz nenájdený
camlp5sch: příkaz nenalezen
camlp5sch: команда не найдена
camlp5sch: командата не е открита
camlp5sch: 命令找不到
camlp5sch: コマンドが見つかりません