DS1307 module doesn't work


I’m trying to add RTC feature to my esp32 board. My ESP32 board has DS1307 RTC chip.
I tested the following example on my board, but it doesn’t work.
When I uploaded the sample code, the board keeps rebooting.

DS1307 is connected to esp32 via I2C(GPIO21 and GPIO22). I didn’t make any change on the example code.
What’s the reason?
Thanks in advance

Finally, I solved this problem
Thanks ok