kdenlive: 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/kdenlive - from package: kdenlive

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

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