I'm receiving the following error on challenge #6 of the Lightning Superbadge:

Challenge Not yet complete... here's what's wrong: 
There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Delete failed. First exception on row 0 with id 0035000002hUBgRAAW; first error: DELETE_FAILED, Your attempt to delete Sam the ninja could not be completed because it is associated with the following adventure packages.: null, null : []

Looking at the Developer Console, it looks like the code which checks the system is forgetting to delete the Adventure Package records before deleting the Contact. Has anyone else run into this issue?

Thank you!

Hi All, 

I am trying to prevent people double booking a piece of equipment out. The user uses the custom object Booking Request to book out equipment for certain dates. 
For example Mike books equipment1 from the 22/06/2016 until 24/06/2016, then someone else wants to book the same piece of equipment from the 23/06/2016 until 25/06/2016 but should not be allowed as it is already booked.

I have created the following trigger which is working if someone enters the same start date, but how do i stop the record saving if they book in between the start and finish date? Any help greatly appreciated.

trigger DuplicateBookingTrigger on Booking_Request__c (before insert, before update) {
  for (Booking_Request__c br:Trigger.new)
  {
      List<Booking_Request__c> b=[select ID from Booking_Request__c where Equipment_Code__c=:br.Equipment_Code__c and Start_Date__c=: br.Start_Date__c and Finish_Date__c=: br.Finish_Date__c];
      if(b.size()>0)
      {
          br.adderror('The equipment selected is already booked for this date');
      }
   }