You cannot pass Qt.formatDateTime() string to qsTr() translation function as an argument

import QtQuick 1.0

Rectangle {
    width: 300; height: 200
    Column {
        anchors.centerIn: parent
        Text {
            text: {
                var date = new Date();
                return qsTr("This works, date %0").arg(Qt.formatDateTime(date, "hh::mm") + " ");
            }
        }
        Text {
            text: {
                var date = new Date();
                // returns empty string
                return qsTr("This doesn't, date %0").arg(Qt.formatDateTime(date, "hh::mm"));
            }
        }
    }
}