bts: 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/bts - from package: devscripts

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

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