Missing Lease

We are receiving payments for a well in Carter County. I cannot find a copy of the lease and have checked on the OK County Records website and cannot find it. Looking at the recent Division order we signed, it is noted that the current payee is now making payments because of an operator change to the well. I then asked the Lessor for a copy and they say they don’t have one. How can they be paying us without a copy of the signed lease from the previous operator? How do I go about finding the original lease?