ProgressBar does not show progress if style has been

import QtQuick 2.1
import QtQuick.Controls 1.0
import QtQuick.Controls.Styles 1.0

Rectangle {
    width: 300
    height: 400

    color: "red"

    ProgressBar {
        width: 200
        height: 50

        style: ProgressBarStyle {
            background: Rectangle {
                radius: 2
                color: "lightgray"
                border.color: "gray"
                border.width: 1
                implicitWidth: 200
                implicitHeight: 24
            }
            progress: Rectangle {
                color: "lightsteelblue"
                border.color: "steelblue"
            }
        }

        anchors.centerIn: parent

        indeterminate: true
    }
}