Why the nRF52 DK and nRF9160 DK are not connecting via Bluetooth?

[ntnudokka]

We have bought one nRF52 DK and one nRF9160 DK with proper programming (the nRF9160 is able to connect to the cloud via cellular network), but the two devices are not able to connect via bluetooth, May we know why?

[Vish]

The board controller nRF52840 on nRF9160DK should have the correct firmware.   Have you used this example? 

developer.nordicsemi.com/.../README.html