Did it happen before on EAD application?

Dear All:

Thanks for all of your kind helps. Last week, I posted some questions on my EAD-C-9 application. INS requested the additional evidence, which is the evidence for my pending I-485. I feel so confused and strange. I definetly submited my receipt notice for my I-485. Did they lose my I-485 receipt? Or did they overlook that document? But I have to fedex them my receipt notice for my I-485 pendng again.

Appreciate that you would let me know what could happen? Thanks again in advance.