The week before and the week after Labor Day, many firms are ghost towns. Partners are taking end-of-summer vacations and, even more so, their clients (especially if transactional) are doing the same. There's a lull between when most summer associates leave and most call-backs take place. Next week, things will crank back up, i.e., everyone involved with summer hiring will be back to the office, attending the weekly hiring meetings (or submitting emails, or whatever they do to vote yes or no at a given firm), etc. Good luck.