plasma-remote-helper: 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/plasma-remote-helper - from package: kde-runtime

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

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