Fiat

This is so embarrassing to have to ask, but i cannot secure the fuel cap of my car. i know i managed to close it once or twice but ever since, i cannot lock it. i know the cap is ok, it is definitely not broken. what is the proper way to lock it?

I had this problem several times as sometimes its frustrating trying to lock the fuel cap. once u open it leave the key as it is in the lock. when u come to close it, put the cap on and turn the key 90degrees to the right. once its locked turn the key opposite way slightly and remove the key. thats the way it should be locked, but yes sometimes it needs some playing. good luck :)