BEAGLE-3P-BBONE-AI: USB Device Firmware Upgrade

Hello everyone!
I use the beaglebone-ai development board, the chip is am5729.
I followed the section (USB Device Firmware Upgrade) of the Processor SDK Linux.
I use “make am57xx_evm_defconfig” to build uboot, and enable the SPL-DFU feature.
When I execute “sudo usbboot-stand-alone -S spl/u-boot-spl.bin”, the following prompt appears:
“reading ASIC ID
CHIP: 5641
rom minor version: 02
IDEN: 0000000000000000000000000000000000000000
MPKH: 0000000000000000000000000000000000000000000000000000000000000000
CRC0: 51d2f9a7
CRC1: 00000000
device is GP
sending 2ndstage to target…”
When I execute “sudo dfu-util -l”, there was no prompt “Found DFU: xxxxxxxxx”.
So where is the problem?