txt2lps: 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/txt2lps - from package: mcrl2

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

Error in other languages:
txt2lps: bevel nie gevind nie
txt2lps: comandă negăsită
txt2lps: comando não encontrado
txt2lps: commande introuvable
txt2lps: command not found
txt2lps: käsku ei ole
txt2lps: không tìm thấy lệnh
txt2lps: komanda nerasta
txt2lps: Kommando nicht gefunden.
txt2lps: kommandot finns inte
txt2lps: komut yok
txt2lps: nie znaleziono polecenia
txt2lps: níor aimsíodh an t-ordú
txt2lps: no se encontró la orden
txt2lps: no s'ha trobat l'ordre
txt2lps: opdracht niet gevonden
txt2lps: parancs nem található
txt2lps: perintah tidak ditemukan
txt2lps: príkaz nenájdený
txt2lps: příkaz nenalezen
txt2lps: команда не найдена
txt2lps: командата не е открита
txt2lps: 命令找不到
txt2lps: コマンドが見つかりません