mod2html: 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/mod2html - from package: libpod-tree-perl

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

Error in other languages:
mod2html: bevel nie gevind nie
mod2html: comandă negăsită
mod2html: comando não encontrado
mod2html: commande introuvable
mod2html: command not found
mod2html: käsku ei ole
mod2html: không tìm thấy lệnh
mod2html: komanda nerasta
mod2html: Kommando nicht gefunden.
mod2html: kommandot finns inte
mod2html: komut yok
mod2html: nie znaleziono polecenia
mod2html: níor aimsíodh an t-ordú
mod2html: no se encontró la orden
mod2html: no s'ha trobat l'ordre
mod2html: opdracht niet gevonden
mod2html: parancs nem található
mod2html: perintah tidak ditemukan
mod2html: príkaz nenájdený
mod2html: příkaz nenalezen
mod2html: команда не найдена
mod2html: командата не е открита
mod2html: 命令找不到
mod2html: コマンドが見つかりません