Changes to Animation's 'to' and 'from' properties ignored while animating

import QtQuick 1.1
Item {
    width: 950
    height: 500

    Rectangle {
        id: blueRect
        color: "blue"
        width: 500; height: 300

        Rectangle {
            id: redRect
            color: "red"
            width: 50
            height: 50
            anchors.verticalCenter: parent.verticalCenter
        }

        SequentialAnimation {
            id: anim
            running: true
            loops: Animation.Infinite
            NumberAnimation {
                target: redRect; property: "x"
                from: 0; to: blueRect.width-redRect.width
                duration: 1000
            }
            NumberAnimation {
                target: redRect; property: "x"
                from: blueRect.width-redRect.width; to: 0
                onFromChanged: print("new from value: " + from)
                duration: 1000
            }
        }
    }

    MouseArea {
        anchors.fill: parent
        onClicked: {
            blueRect.width = mouse.x;
            blueRect.height = mouse.y;
//            anim.restart();
        }
    }
}