Hello Muhamed,
Make sure you're following all the step of the documentation for the mobile scenarios. Make sure you got all the options to debug (and your phone is ready for it). For Troubleshooting also check this topic.
To test a mobile app on an Android device:
- In your device turn USB debugging ON.
- Connect your mobile device to the PC through a USB cable.
- In your device allow PC for debugging on the device.
Happy debugging! Cheers!