lts2pbes: 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/lts2pbes - from package: mcrl2

You may install the required package with command apt-get install {package}
Error in other languages:
lts2pbes: bevel nie gevind nie
lts2pbes: comandă negăsită
lts2pbes: comando não encontrado
lts2pbes: commande introuvable
lts2pbes: command not found
lts2pbes: käsku ei ole
lts2pbes: không tìm thấy lệnh
lts2pbes: komanda nerasta
lts2pbes: Kommando nicht gefunden.
lts2pbes: kommandot finns inte
lts2pbes: komut yok
lts2pbes: nie znaleziono polecenia
lts2pbes: níor aimsíodh an t-ordú
lts2pbes: no se encontró la orden
lts2pbes: no s'ha trobat l'ordre
lts2pbes: opdracht niet gevonden
lts2pbes: parancs nem található
lts2pbes: perintah tidak ditemukan
lts2pbes: príkaz nenájdený
lts2pbes: příkaz nenalezen
lts2pbes: команда не найдена
lts2pbes: командата не е открита
lts2pbes: 命令找不到
lts2pbes: コマンドが見つかりません