Request your realtor to speak with the listing agent to try to determine what the sellers took exception with. If your effort reveals there isn't anything acceptable it may be advisable to begin over with another offer if you have tha ability to do so.
There are too many factors for us to tell you what to do or why the sellers did not counter.
Did you Realtor ask the listing agent for a counter?
Usually the Realtors can discuss what happened and find a way to move forward.
If you low ball an offer many sellers dont counter offer find waste of their time.
~ National Featured Realtor and Consultant, Lecturer regarding Credit Repair, Mortgage Loan Officer