Problem connecting Victron Connect app. to camper.

I'm familiarizing myself with my new TAB400 and all is well until I want to monitor the Lithium battery and solar charger. Using my iPhone I have downloaded the app and ensured Bluetooth is on.. When I open the app it tries to find the controller so it can pair. But it cannot  - I get a message "No devices found". I have read the manual but it assumes you're paired.

Is there something I'm missing? Is there a switch on the device that needs to be turned on? The inverter is running, all lights etc are working as is shore power. Any help appreciated! I'm a complete newly when it comes to the Lithium Package.

Bill