I have the 3 wire Voltmeter Ammeter DC4.5-30V Voltage Current Meter 2-in-1 Digital Multimeter 10A https://www.amazon.com/gp/product/B00GJK1FGI/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

It is working correctly to measure voltage and current on a circuit that has 6 different loads. I have it wired in at the power distribution block. This lets me monitor the total load as various loads are switched on and off.

However, one of the loads requires lower voltage (at very exact tolerances). I have aDROK Numerical Control Step Down Voltage Regulator Stabilizer, DC 6-55V to 0-50V 5A Constant Voltage Current Buck Power Converter Voltage Transformer

https://www.amazon.com/gp/product/B01FNVESV2/ref=oh_aui_detailpage_o03_s02?ie=UTF8&psc=1

It works perfectly if I connect it directly to my power supply or if I connect it to my power distribution block and remove the DROK meter. If I have the DROK volt/amp meter in the circuit and try to have the DROK regulator as a load, it does not work. I get voltage to the input side of the regulator but no voltage on the output side. Again, If I remove the volt/amp meter then it works correctly.

Can you provide any help?