Problem with configuration of plug in

i comfigure the plug in with flat rates for every country on the world with weight shipping method but when i test it and i bye one item or many items with weight 1 or 2 kg the plug in its says at the cart only the back up rate not the original rate that ive add it )i ve add different rate for 1 kg for 2 kg etc and differents rates for differents countries. in my wordpress site in my woocomerce products in every product i have the price the weigh the heigh in grammars becouse woocomerce is only accept in grammars not in kg. why my ups plug in not working well_ i have done something wrong ?