lxsession-logout: 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/lxsession-logout - from package: lxsession

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

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