Hello,

I'm ripping my hair out over this wizard controller. I made this off of the Cookbook's Opportunity controller. Basically, if I comment this out, the participant assessment is created/inserted successfully.

//participantanswer.Participant_Assessment__c = participantassessment.Id;
      //participantanswer.Possible_Answer__c = possibleanswer1;
      //insert participantanswer;

Without that block commented, my controller looks like this, and I cannot seem to pull the newly created Id of the participantassessment which was successfully  created in the previous block. 

public class osmController {

   // These member variables maintain the state of the wizard. 
   // When users enter data into the wizard, their input is stored 
   // in these variables.  
    
   Participant_Assessment__c participantassessment;
   Participant_Answer__c participantanswer;
   private final Participant__c participant;
   private final Assessment__c assessment;
   string possibleanswer1 = null;

   // The next methods return one of each of the member 
   // variables. If this is the first time the method is called, 
   // it creates an empty record for the variable. 
   
   public osmController() {

            participant = [select id, name from Participant__c where id =
                       :ApexPages.currentPage().getParameters().get('id')];
                       
            assessment = [select id, name from Assessment__c where Name = 
            		   :ApexPages.currentPage().getParameters().get('asmt') AND
            		   Version__c = :ApexPages.currentPage().getParameters().get('version')];
            		   
   }
      
   public List<selectOption> getanswer1() {
        List<selectOption> options = new List<selectOption>(); //new list for holding all of the picklist options
        //options.add(new selectOption('', '--None--')); //add the first option of '- None -' in case the user doesn't want to select a value or in case no values are returned from query below
        for (Possible_Answer__c pa1 : [SELECT Id, Answer_Display__c FROM Possible_Answer__c
         WHERE Dimension__c = 'Income']) { 
            options.add(new selectOption(pa1.Id, pa1.Id)); //for all records found - add them to the picklist options
        }
        return options; //return the picklist options
   }
   
   public Participant__c getParticipant() {
            return participant;
   }
   
   public Assessment__c getAssessment() {
            return assessment;
   }   
   
   public Participant_Assessment__c getParticipantAssessment() {
      if(participantassessment == null) participantassessment = new Participant_Assessment__c();
      return participantassessment;
   }
   
   public Participant_Answer__c getParticipantAnswer() {
      if(participantanswer == null) participantanswer = new Participant_Answer__c();
      return participantanswer;
   }  
    
   public String getpossibleanswer1() {
            return possibleanswer1;
   }   
   
   public void setpossibleanswer1(String possibleanswer1) { this.possibleanswer1 = possibleanswer1; }
   


   // The next methods control navigation through 
   // the wizard. Each returns a PageReference for one of the pages 
   // in the wizard. Note that the redirect attribute does not need to 
   // be set on the PageReference because the URL does not need to change 
   // when users move from page to page. 
    
   public PageReference step1() {
      return Page.osmStep1;
   }

   public PageReference step2() {
      return Page.osmStep2;
   }

   public PageReference step3() {
      return Page.osmStep3;
   }
   
   // This method cancels the wizard, and returns the user to the  
   // Participants tab 
    
    public PageReference cancel() {
            PageReference participantPage = new ApexPages.StandardController(participant).view();
            participantPage.setRedirect(true);
            return participantPage; 
    }
    
   // This method performs the final save for all objects, and 
   // then navigates the user to the detail page for the new 
   // participant assessment. 
    
   public PageReference save() {

      // Create the participant assessment. Before inserting, use the id field 
      // from the active participant and assessment that are passed via custom button to create 
      // the relationship between the participant and assessment and the participant assessment. 
    
      participantassessment.Participant__c = participant.Id;
      participantassessment.Assessment__c = assessment.Id;
      insert participantassessment;

      // Create the participant answer. Before inserting, use the id field 
      // that's created once the participant assessment is inserted to create 
      // the relationship between the participant assessment and the participant answer. 
    
      participantanswer.Participant_Assessment__c = participantassessment.Id;
      //participantanswer.Possible_Answer__c = possibleanswer1;
      insert participantanswer;

      // Finally, send the user to the detail page for  
      // the new participant assessment. 
    
      PageReference participantassessmentPage = new ApexPages.StandardController(participantassessment).view();
      participantassessmentPage.setRedirect(true);

      return participantassessmentPage;
   }
   
}

Any tips on how to go about fixing/debugging this would be greatly appreciated.

 The exact error I get is:

 System.NullPointerException: Attempt to de-reference a null object

Class.osmController.save: line 109, column 1     

Line 109 is 

participantanswer.Participant_Assessment__c = participantassessment.Id