Gatling test i'm having trouble running on Flood

ReserveTickets.scala

import io.gatling.core.Predef._
import io.gatling.http.Predef._

import scala.concurrent.duration._

import java.util.Date._
import java.text.SimpleDateFormat._

// Mandatory, you must import Flood libraries
import flood._

class TestPlan extends Simulation {
  // Optional, Tricentis Flood will pass in threads, rampup and duration properties from UI
  val threads   = Integer.getInteger("threads",  100)
  val rampup    = java.lang.Long.getLong("rampup", 30L)
  val duration  = java.lang.Long.getLong("duration", 300L)

  // Mandatory, you must use httpConfigFlood
  val httpConf = httpConfigFlood.baseURL("https://core.staging.laneone.com/")

  val myScenario = scenario("scenario")
    .during(duration seconds) {

      exec(
        http("Reserve some tickets")
          .post(_ => s"test_api/reserve_tickets")
          .body(StringBody(session => s"""{ "event_id": "1148", "ticket_quantity": "2" }""")).asJSON
          .basicAuth("****", "****")
          .asJSON
          .check(status.in(200, 201))
      )

    }

  setUp(myScenario.inject(rampUsers(threads) over (rampup seconds))).protocols(httpConf)
}