PPPD over usb serial

Hi,
I am using a serial gadget (usb) which is connected to linux host.

I want to run pppd on usb.


On gadget side : i get the error:

Couldn't set tty to PPP discipline: Invalid argument

On Host Side:
I get the messages:

Using interface ppp0
Connect: ppp0 <--> /dev/input/ttyACM0
LCP: timeout sending Config-Requests
Connection terminated.

my option file are

host side :
/dev/input/ttyACM0
9600
noauth
nocrtscts
nodetach
1.1.1.1:1.1.1.2




gadget side:

/dev/ttygserial
9600
noauth
nocrtscts
nodetach
local


What is wrong ?.


I would appreciate any help on this matter ?.



Regards,
Maximus