Possible causes:
1. The app doesn't have permission to access the data network.
2. App error.
3. System error.
Solutions:
1. Check if the app has network permission.
2. Uninstall and reinstall the app.
3. Restart the phone or restore the phone to factory settings.
4. Test whether the app works on other phones. If not, please contact the developer for assistance.
If the issue persists, contact our Customer Support for further assistance.