Problem with netinstall

Hi…
I have problem with netinstall..
My routerboard 411 failed after trying to upgrade from version 4 to version 5…

Now, when I try to load with netistall 4.17, I got this error:

trying bootp protocol… OK
Got IP address: 192.168.1.2
resolved mac address DC:0E:A1:E6:8A:ED
transfer started … transfer ok, time=2.38s
setting up elf image… OK
jumping to kernel code
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)


But, when I tried to load netinstall 5.21, I same error…

Please help…
Dorijan