If the property is under a valid existing lease, then you will not get a new lease. There should be a recorded lease or memorandum of lease on file. Is it possible that your grandmother was not the original lessee, but inherited or purchased the minerals after they were leased by another family member (grandfather, aunt, etc) or a third party? The operator should be able to give you a reference as to the filing. Otherwise, you will need to do a title search from your grandmother back in time to find the original owner or lessee. Sometimes a name is spelled incorrectly in the system.