mpic++.lam: 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/mpic++.lam - from package: lam4-dev

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