Tracking number says delivered but Buyer says they don't have it

When I lived in an apartment the delivery man would take it to the main office and leave it there. The problem was that he would sign off that it was delivered but would not leave us a note indicating that he had done that.
 
Thanks everyone for your input!
He asked the post man today and it was accidentally delivered to the building across the street. The postman retrieved it and he got his package! Phew. I'm just happy he got it back!