Deploy DJI windows SDK Sample to Mavic air - error DEP6200: device not found。SmartDeviceException - deploy fail [0x80131500]

I am trying to deploy DJI Windows SDK Sample application UWP from VS2017 15.9.9 from windows10 to a dji mavic air.

1.Windows 10 has enabled Developer Mode in "For Developers" settings.

2.The mavic air remote control is connected mini usb to the windows 10.

3.The mavic air has switch to WIFI mode, and windows10 connected wifi to drone.

However, deploy fails with error:

DEP6200: Bootstrapping failed. Device cannot be found. 
SmartDeviceException - Deployment failed because no device was detected. 
Make sure a device is connected and powered on. [0x80131500] 

Any idea?

Thanks.