STTY echo can't be turned on

On the Apalis TK1 running the BSP v2.7b3 the serial console has by default echo turned off. And I’m unable to set it on using stty /dev/ttyS0 echo This command fails. Is there any way around it?

I didn’t see this with the previous BSPs.

Isn’t it stty -F /dev/ttyS0 echo?

Nope. Still not working.

root@tegra-ubuntu:/home/ubuntu# stty: /dev/ttyS0: unable to perform all requested operations

Hi I tried the command

sudo stty -F /dev/ttyS0 echo

with the Linux tegra-ubuntu 3.10.40-2.7.5 and BSP 2.7b3. It is working fine.
Which version of Ubuntu are u using?