diagraphica: 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/diagraphica - from package: mcrl2

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

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