Your 'Counter' mechanism doesn't work. It keeps increasing, and then you are telling the script to pick the Counter instance, but once the Counter value gets over 10, there aren't 10 strawberries to pick from. You need to devise a better mechanism for picking random strawberries to delete. Try: int(random(0,Rock.Count))
Oh, and the default size of the Array is 10! Increase the number of elements.