We purchased agriculture land 2018 from vender, we got passbook and shown in dharani site also, but recently what we knowed that vendor is given agrement of sale com gpa to x person, he registered that document in 2005 in registration office, but that x person died in 2011, that registerd document shown in EC, but our registration time we didn't see that one properly.if x person was died is that document is Valid or not, is our property got any problems in future. What will do next.