Why did they go OTD

Reading Shmuel 1 chapters 7 and 8, the navi presents a sad situation… Shmuel (Samuel) the prophet spends his life doing Hashems work. He appoints his kids Shoftim (tribal judges). The navi then documents both were corrupt and took bribes..

Question 1. How could he not have been aware his kids were not worthy?

Question 2. What did he do wrong as a father? This is a common theme in tanach father’s screwing up (Shmuel’s father didnt even raise him)