mkcamlp4: 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 CentOS possible default full paths are:

/usr/bin/mkcamlp4 - from package: ocaml-camlp4-devel

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/mkcamlp4 - from package: camlp4

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

Error in other languages:
mkcamlp4: bevel nie gevind nie
mkcamlp4: comandă negăsită
mkcamlp4: comando não encontrado
mkcamlp4: commande introuvable
mkcamlp4: command not found
mkcamlp4: käsku ei ole
mkcamlp4: không tìm thấy lệnh
mkcamlp4: komanda nerasta
mkcamlp4: Kommando nicht gefunden.
mkcamlp4: kommandot finns inte
mkcamlp4: komut yok
mkcamlp4: nie znaleziono polecenia
mkcamlp4: níor aimsíodh an t-ordú
mkcamlp4: no se encontró la orden
mkcamlp4: no s'ha trobat l'ordre
mkcamlp4: opdracht niet gevonden
mkcamlp4: parancs nem található
mkcamlp4: perintah tidak ditemukan
mkcamlp4: príkaz nenájdený
mkcamlp4: příkaz nenalezen
mkcamlp4: команда не найдена
mkcamlp4: командата не е открита
mkcamlp4: 命令找不到
mkcamlp4: コマンドが見つかりません