When you say "lightning bolt cable", what do you mean?
I hope that you are not trying to use one of these to connect a (Mini) DisplayPort display.
Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter - Apple
This adapter only carries Thunderbolt from one side to the other. It does not know how to make the Thunderbolt 2 side (which has a Mini DisplayPort socket) act as a Mini DisplayPort. If you are trying to connect a USB-C port on a Mac to a (Mini) DIsplayPort on a monitor, you want a USB-C to (Mini) DIsplayPort adapter or adapter cable. You can find these on places like Amazon, and they are much cheaper than the TB3-to-2 adapter.
Which MacBook Pro are you trying to connect to which BenQ monitor?