Perhaps the graveyard is full and there are no longer graves for sale. In the past ,one could buy a grave ahead of time but in some areas you can no longer do this as there were too many empty graves in a graveyard and it meant local authorities were being made get new graveyards without the existing one being full.
My in-laws had a empty grave in the west and had left that area and no longer had use for it. I contacted the local council and they bought it back. It cost 12 Pounds in the 1960's and they got 250 Pounds from the council for it in the 1990's. The mother in law was chuffed at their real estate investment!!!