Animation in Qml

Question

I'm trying to make a slow change of color in my code but my program waits for 1.5 secs and then changes color instantly. My development environment is Windows 8. How can i fix this? Here is my code:

Rectangle {
    color: "green"
    width: 300
    height: 300
    ColorAnimation on color {
        to: "red"
        duration: 1000
    }
}