isotpsend: 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/isotpsend - from package: can-utils

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

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