USB-C (Thunderbolt) port not working

Hello

I own a Dell xps 13 9350 laptop.
I'm trying to connect an external monitor through the Thunderbolt 3 port, with a USB-C to VGA adapter, but the laptop does not recognize that I've connected an external device at all.

I suspect that maybe I'm missing a driver, I've tried installing Intel(R) Thunderbolt(TM) Controller Driver: "Chipset_Driver_D91CC_WN32_16.1.47.275_A02.EXE" 
but it was no good, still not working.

How can I troubleshoot this? Could it be a different driver that's missing?

Thanks
Shahar