Problems connecting Raspberry Pi to M100 via serial port

I am currently trying to install the raspberry pi 3 as my embedded device on my M100. I connect my pi by connecting the UART_CAN2 port to the GND, TXD and RXD pins of my pi with the provided UART serial cable. I am using the 3.1 SDK branch provided by DJI on Github which is compatible with the M100. When I try to execute djiosdk-linux-sample from my build directory it looks like this:

User Configuration read successfully. 

These are your User_Config settings.
Serial port = /dev/ttyS0
Baudrate = 115200
Drone/FC Version: M100
SDK Version: 3.1
App ID: MY_APP_ID_XXXXXXX
App Key: MY_APP_KEY_XXXXXXXXXXXXXXXXXXXXXXX

Does everything look correct? If not, navigate to Linux/UserConfig.txt and make changes.

STATUS init,line 51: Attempting to open device /dev/ttyS0 with baudrate 115200...
STATUS init,line 60: ...Serial started successfully.

Attempting activation..
Automatic activation successful.
Failed to obtain control.
Your RC mode switch is not in mode F. (Is the RC connected and paired?)
This program will exit now.

      

        
        
        
      

    

I know this question has been asked before, but I haven't found any convincing answers. My remote is in F mode and it's recognized like this in the Assistant app. However, I know this is not a problem. I have heard from other people on the internet ( https://github.com/dji-sdk/Onboard-SDK/issues/77 ) that the remote control and its mode are not the core of the problem. Does anyone know how to solve this? Any help would be great.

Thanks, AWATHIEU