lpsconstelm: 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/lpsconstelm - from package: mcrl2

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

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