backintime-askpass: 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/backintime-askpass - from package: backintime-common

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

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