Greetings.

I purchased the DC-DC buck converter listed in the title (and here is the amazon link https://www.amazon.com/DROK-Converter-Step-down-Adjustable-Regulator/dp/B017SLMVXM/ref=sr_1_51?m=AFHAE9RJVUMB&s=merchant-items&ie=UTF8&qid=1472070275&sr=1-51&keywords=red+led+display)

I also purchased this boost converter:
https://www.amazon.com/DROK-Regulator-Adjustable-Converter-Transformer/dp/B019SYX7BM/ref=sr_1_2?m=AFHAE9RJVUMB&s=merchant-items&ie=UTF8&qid=1472073099&sr=1-2&keywords=boost+10A

My setting was: A 12V battery (currently measuring 13.8V) will be attached to the boost converter, the boost will be set to 16V and then the buck will receive the 16V and step it down to 12V. I first connected the boost converter, set it to 16V output and no problem.

Then I connected it to the buck converter and powered the whole system, as soon as I power it, then both converters shut down immediately. I thought the problem was the buck converter, so I connected it to the 12V battery and test it by stepping down to 9V. When I turn on the system, it no longer shuts down, but the buck converter output voltage is the same (minus the normal operating drop) in the converters input and output (input=13.8 output=13.6). Turning the adjustment potentiometer either way does nothing, the output voltage remains as stated previously. So

1) Which way should I turn the adjustment potentiometer to decrease the output voltage?
2) Why is the buck converter not functioning?
3) Why do the converters shut down when they are together? Why do they stay on when separated but shut down when connected as I stated?