I just cant work out this shipping rate stuff..

My cart contents are shown in kg, for example, a small item 1kg

If i set up my rates as follows:

zone 1 countries (just france for now)
FR

zone 1 shipping
1:10,2:20,3:30

you would expect to get a shipping cost of 10ukp for the 1kg item?

As i understand it
0-1kg=10UKP
1-2kg=20UKP
2-3kg=30UKP

Well i get
"Zone Rates (The shipping rate cannot be determined at this time)"

I am assuming the weights in the shipping table are in KG?
The shipping address for the items is france.

please help..!