ltpanel: 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/ltpanel - from package: ltpanel

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

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