VAST: Unable to request ads from server. Cause: Error #2048

I am getting error in testing VAST using passing URL of XML file but if i am trying to pass XML code than it's working fine.

VAST Testing Site:

http://ift.tt/1lLz8w4

http://ift.tt/1lLz8w8

VAST Tag Content

<?xml version="1.0" encoding="utf-8"?>
<VAST version="2.0">
    <Ad id="Adotube">
        <InLine>
            <AdSystem version="3.0">Webtech91</AdSystem>
            <AdTitle>My First Testing VAST</AdTitle>
            <Description>N/A Description</Description>
            <Impression>
                <![CDATA[http://ift.tt/1lLzbrC;
            </Impression>
            <Creatives>
                <Creative sequence="1" id="oRYYzvQ">
                    <Linear>
                        <Duration>00:00:13</Duration>
                        <TrackingEvents>
                            <Tracking event="firstQuartile">
                                <![CDATA[http://ift.tt/1lLzbrE;
                            </Tracking>
                            <Tracking event="midpoint">
                                <![CDATA[http://ift.tt/1oz9mA2;
                            </Tracking>
                            <Tracking event="thirdQuartile">
                                <![CDATA[http://ift.tt/1lLz8wa;
                            </Tracking>
                            <Tracking event="complete">
                                <![CDATA[http://ift.tt/1oz9mA4;
                            </Tracking>
                        </TrackingEvents>
                        <VideoClicks>
                            <ClickThrough>
                            </ClickThrough>
                        </VideoClicks>
                        <MediaFiles>
                            <MediaFile delivery="progressive" bitrate="600" width="640" height="360" type="video/mp4">
                                <![CDATA[http://ift.tt/1lLzbrG;
                            </MediaFile>
                            <MediaFile delivery="progressive" bitrate="600" width="640" height="360" type="video/x-flv">
                                <![CDATA[http://ift.tt/1oz9krI;
                            </MediaFile>
                            <MediaFile delivery="progressive" bitrate="600" width="640" height="360" type="video/webm">
                                <![CDATA[http://ift.tt/1lLz8Mq;
                            </MediaFile>
                        </MediaFiles>
                    </Linear>
                </Creative>
            </Creatives>
        </InLine>
    </Ad>
</VAST>

I found somewhere that may be it's an cross browser issue so i put following code but still not working:

<?xml version="1.0" encoding="utf-8"?>
<cross-domain-policy><allow-access-from domain="*"/></cross-domain-policy>
<VAST version="2.0">

URL sample:

http://ift.tt/1oz9mQk