Applicant Status And Change Reason Is Not Updating

Symptoms

Problem Statement:

Applicant status and change reason is not updating if any of old value or new value for change reason is null

Steps:
The issue can be reproduced at will with the following steps:

1. Log into Oracle Application using HRMS Manager 
2. Navigate to People > enter and Maintain 
3. Find Internal Applicant with existing applications 
4. Click Others... button
5. Select Application and click OK button
6. Date track to 15-Apr-2011 and update Reason to 'Under Referral' 
7. Click Save button 
8. Date track to 03-May-2011 and update Status to 'Accepted' 
   and Reason to 'Offer Accepted'
9. Click Save button with Update option.
10. Log into Oracle Applications using  iRecruitment Recruiter responsibility
11. Click recruitment Center Home link
12. Click Vacancies tab
13. Search for the vacancy applied for by the applicant
14. Click on the number of applicants link
15. Click on the Applicant Name link
16. Check the records in the  Application Assignment History region

  --> Missing 'Under Referral'  record

business Impact:
The issue has the following business impact:
Due to this issue, users cannot know in which circumstances the status has been changed whatever the applicant type is: internal or external.

Remark:
When a future Dated Interview is recorded, Irecruitment shows the latest status. That means in case you record 2 interview dates whose one is future dated, the application status will reflect second interview. That is the normal behaviour of the Irecruitment. 

Cause