lpssuminst: 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

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/lpssuminst - from package: mcrl2

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