Nsdl says documents not received

I applied for a pan card for my parents. I took the printout of the forms and sent them along with relveant documents to NSDL for processing. I sent the documents through speed post. Online tracking says that documents for both the parents were delivered on January 6, 2017.

When I checked the application status for my mother, it says that NSDL hasn't received the supporting documents. How is it possible when the Post Office has already delivered them 5 days ago?