Define Image in XML from SDCard on Android

i still confuse about calling image from SDCard in XML. I using XmlPullParser on Android for parsing my XML. But I failed to load file on SDCard.

it's my XML :

<image>
    <imageproperty>
        <id>1</id>
        <title>Image1</title>
        <thumb_url>file:///mnt/sdcard/image1.png</thumb_url>
    </imageproperty>
    <imageproperty>
        <id>2</id>
        <title>Image2</title>
        <thumb_url>file:///mnt/sdcard/image1.png</thumb_url>
    </imageproperty>
</image>

but, I'm using url from web, it can be loaded.

<image>
    <imageproperty>
        <id>1</id>
        <title>image1</title>
        <thumb_url>http://ift.tt/1oTEnRI;
    </imageproperty>
    <imageproperty>
        <id>2</id>
        <title>image2</title>
        <thumb_url>http://ift.tt/1oTEnRI;
    </imageproperty>
</image>

any suggestion? Maybe, I miss something.

Thanks!