"Davide
in adv settings i put to change to slick only AFTER 10 laps that it stoped raining...it was just raining! :(((
So once weather turns overcast/cloudy/sunny after 10 Laps auto-pit kicks in at the end of sector 2 selecting the compound you set. If you select a tyre yourself before starting sector 3 auto-pit will overwrite the tyre choice, wait until you see the car is pitting then select the tyre you want to make sure you get the tyre you want :)