CCS/AM4379: ptp question

Part Number: AM4379

Tool/software: Code Composer Studio

I am using  AM4379 board  IDK-AM437X

  running in Linux

I wnat to keep the PC(ubuntu) time the same to my Baord

using the ptp

following "Testing CPTS/PTP" in

 http://software-dl.ti.com/processor-sdk-linux/esd/docs/latest/linux/Foundational_Components_Kernel_Drivers.html#common-platform-time-sync-cpts

And I can see it works!

Host(ubuntu):sudo  ./ptp4l -E -2 -H -i enp4s0 -l 7 -m -q -p /dev/ptp0 
Slave(board):sudo ./ptp4l -E -2 -H -i eth0 -s -l 7 -m -q -p /dev/ptp0

But I have a problem:

My board shows:

PC shows:

But the timestamp is not the same!

timestamp of My PC:

My board timestamp:

So what is the reason maybe?