Problem to run MAVProxy

Dears,

I am new in the community. We are trying to run the tutorial to run MAVProxy and DroneKit

python.dronekit.io/guide/getting_started.html

We follow exactly as mentioned by the tutorial (using Ubuntu), we run the initial script with code:

set moddebug 1
module load graph

Then we have the following output:

Connect /dev/ttyUSB0 source_system=255
Logging to mav.tlog
Running script /home/viviano/.mavinit.scr
-> set moddebug 1
-> module load graph
Loaded module graph
MAV>

After that, we cannot run any command. All commands we try return no output, neither an error message. For example, when we try to run vehicle_state.py (only work from script, not from prompt), we have the output:

<droneapi.module.api.MPVehicle object at 0x7ff5b2f4bad0>

Get all vehicle attribute values:
Location: Location:lat=None,lon=None,alt=None,is_relative=False
Attitude: Attitude:pitch=None,yaw=None,roll=None
Velocity: [None, None, None]
-> module load graph
GPS: GPSInfo:fix=None,num_sat=None
Loaded module graph
Groundspeed: None
Airspeed: None
MAV> Mount status: [None, None, None]

Could anybody help us?

Best regards,
Alisson Brito