i686-w64-mingw32-ocamlmktop: 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/i686-w64-mingw32-ocamlmktop - from package: ocaml-mingw-w64-i686

You may install the required package with command apt-get install {package}
Error in other languages:
i686-w64-mingw32-ocamlmktop: bevel nie gevind nie
i686-w64-mingw32-ocamlmktop: comandă negăsită
i686-w64-mingw32-ocamlmktop: comando não encontrado
i686-w64-mingw32-ocamlmktop: commande introuvable
i686-w64-mingw32-ocamlmktop: command not found
i686-w64-mingw32-ocamlmktop: käsku ei ole
i686-w64-mingw32-ocamlmktop: không tìm thấy lệnh
i686-w64-mingw32-ocamlmktop: komanda nerasta
i686-w64-mingw32-ocamlmktop: Kommando nicht gefunden.
i686-w64-mingw32-ocamlmktop: kommandot finns inte
i686-w64-mingw32-ocamlmktop: komut yok
i686-w64-mingw32-ocamlmktop: nie znaleziono polecenia
i686-w64-mingw32-ocamlmktop: níor aimsíodh an t-ordú
i686-w64-mingw32-ocamlmktop: no se encontró la orden
i686-w64-mingw32-ocamlmktop: no s'ha trobat l'ordre
i686-w64-mingw32-ocamlmktop: opdracht niet gevonden
i686-w64-mingw32-ocamlmktop: parancs nem található
i686-w64-mingw32-ocamlmktop: perintah tidak ditemukan
i686-w64-mingw32-ocamlmktop: príkaz nenájdený
i686-w64-mingw32-ocamlmktop: příkaz nenalezen
i686-w64-mingw32-ocamlmktop: команда не найдена
i686-w64-mingw32-ocamlmktop: командата не е открита
i686-w64-mingw32-ocamlmktop: 命令找不到
i686-w64-mingw32-ocamlmktop: コマンドが見つかりません