Hello
The function getOrderWeight convert the weight of the product between the product weight and the unit set in the shipment.
If the product weight= 20 grams, and the shipment weight unit = Kg, then order_weigth = 0.02.
From the version 2.0.8e, we have added a functionality. Log in as admin on the front end, and you will have some infos displayed
Info: weigth_countries _weightCond orderWeight:0.02 weight_start:100 weight_stop:2000 result:0
I hope those infos can help you to better find out why no shipment is selected