I'm trying to port billing data out of observium via the simple API but I'm only getting null data as below:

{"login":{"success":{"code":"101","msg":"User authentification succeeded"}},"data":[{"timestamp":null,"traf_total":null,"traf_in":null,"traf_out":null},{"timestamp":null,"traf_total":null,"traf_in":null,"traf_out":null},{"timestamp":null,"traf_total":null,"traf_in":null,"traf_out":null},{"timestamp":null,"traf_total":null,"traf_in":null,"traf_out":null}