sisc: 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/sisc - from package: sisc

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