Ethernet Shield 2.0 link not work

I have two ethernet shield 2.0, bur one of this has a problem with the link on the ethernet port.
I connect the shield with arduino mega but when the arduino start the ethernet link on the shield not working
Working only if press the reset button for 2 sec. or more.
The second eth. shield 2.0 work normaly…
Why not working ?

Thank you.