dh_ocamldoc: 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/dh_ocamldoc - from package: dh-ocaml

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

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