gnome-flashback: 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/gnome-flashback - from package: gnome-flashback

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

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