clearly you didnt submit documents to support your work experience thats the reason I think responsible for " authenticity", the documents which support work experience are as below , spp or non spp category application doesnt mater , if you submit these documents you will increase your chances - Fellow member "mead" has different view to strictly follow spp checklist but if you submit extra documents it is better and no harm.
1. Offer letter A real offer letter/appointment letter is of approximately 8 pages. My friend got rejection just because that his offer letter was of 2 pages.
2. Salary slips of last 4 months.
3. ITR of yourself mentioning your salary same as salary slips by your company.
I doubt that VO might have verified your work experience by calling or emailing the work experience letter company and I told you in above post that your doctor did overwriting in your dental treatment that is also a major factor I believe.
TY