I got a new phone, a Motorolla Moto G5 plus.   I've downloaded the dji go app.   I've connected to the Phantom's wifi.   But when I turn on the radio control and my phone, and then open up the DJI go app and click on Camera View, it says that I'm not connected.   Any Ideas on what is causing this?   

It means you are not linked between the RC Unit and the aircraft. Follow the procedure outlined in the manual.

Did you power on all components of the copter system?

Hi there, what's the color of the RC indicator? If it is red, you can link RC to see whether it works.