why is @filename nil

Rakefile

desc "Dump the current production database to a MySQL file"
task :dump_remote, :filename do |t, args|
  if args
    @filename = args[:filename]
  else
    @filename = "db-backups/production_data-#{Time.now.strftime("%Y-%m-%d-%H%M")}.sql"
  end
  puts @filename
end