This is the data format the kml is looking for. It has an area and then a few rates. These have a max and min value.
Yours looks like this when I import from kml.
The x and y are too big and it is not reading it as a rate. Just get rid of them and it should load.
This is the new rate file exported from AOG-Rate
Rate.kml (114.5 KB)
This is what I modified to get it to work.
trentamodulazione-mod.kml (136.5 KB)