premise: Edward Stafford, 4th Baron Stafford (1572 – 16 September 1625) was the son of Edward Stafford, 3rd Baron Stafford and Mary Stanley, daughter of Edward Stanley, 3rd Earl of Derby and Dorothy Howard. He became 4th Baron Stafford on the death of his father in 1603
hypothesis: The 3rd Baron Stafford died after his son became the 4th Baron Stafford.
reason: He died BEFORE his son became the 4th Baron Stafford. The system must not have done understood that the passage of the title was after the death.