commercial part number STM32L412CBT6, USB connection rejected.

[Balaji_1]

I paired the HSE and PLL clocks for the USB to provide 48 MHz and a system clock of 72 MHz. I've seen that the ESOF,RESET, SUSP, and ERR interrupts seem to hit me first and that the CTR interrupt never occurs,based on what I've observed in the USB_ISTR register. I've tried using default endpoints, but I still can't figure out what's creating this problem. Please assist me in solving the issues at hand.