ploticus: 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
/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/ploticus - from package: ploticus

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