Dear RodG,
Thank you very much for your kind attention.
I tried to change in unit pack
However, as per Ajeh' suggestion, I tried
by correcting the Product Quantity Minimum(in my case changed to 180,000)
which can be divisable by Product Quantity Unit(in my case 36,000),
it worked perfectly.

The problem is solved.
Lastly once again thank you very much.

Faithfully,
tsubasa2013