YOMA Multinational Solutions ASP.NET Developer interview questions

I got a mail from Consultancy for the interview.They Schedule interview with YOMA. There was 2 rounds, both round went good and by evening i got a call from YOMA HR that you are shortlisted,please submit your documents then i submit all documents as required by HR. After completion of all the formalities ,i call HR and ask for the further process and ask for the Offer letter then they said we put you on hold.what is this ....why you waste the time..