Null Child Element when Parsing XML with XOM

I am using XOM to parse a xml file, but I am having an issue getting an Element by string name. I am able to access each element by iterating through getChild(x) where x=0:ChildCount, but it seems silly to have to hack my way around the software where there is a built-in function to accomplish this task. Why am I getting an NPE? See the example below...I am 100% sure the parent contains a child with the exact name I am searching for. What can I do to solve this?

FileInputStream xmlFile = new FileInputStream("temp.xml");
Builder builder = new Builder();
Document doc = builder.build(xmlFile);
Element root = doc.getRootElement();

System.out.println(((Element)root.getChild(1)).getLocalName()); //--> prints "player"
Element player = root.getFirstChildElement(((Element)root.getChild(1)).getLocalName()); //--> null
System.out.println(player); //--> prints "null"
Element player_stats = player.getFirstChildElement("player_stats"); //--> NPE

temp.xml

<?xml version="1.0" encoding="UTF-8"?>
<fantasy_content xml:lang="en-US"
yahoo:uri="http://fantasysports.yahooapis.com/fantasy/v2/player/nfl.p.7206/stats;type=week;week=2"
time="34.230947494507ms" copyright="Data provided by Yahoo! and STATS, LLC"
refresh_rate="31" xmlns:yahoo="http://www.yahooapis.com/v1/base.rng"
xmlns="http://fantasysports.yahooapis.com/fantasy/v2/base.rng">
<player>
    <player_key>331.p.7206</player_key>
    <player_id>7206</player_id>
    <name>
        <full>Heath Miller</full>
        <first>Heath</first>
        <last>Miller</last>
        <ascii_first>Heath</ascii_first>
        <ascii_last>Miller</ascii_last>
    </name>
    <injury_note>not injury related</injury_note>
    <editorial_player_key>nfl.p.7206</editorial_player_key>
    <editorial_team_key>nfl.t.23</editorial_team_key>
    <editorial_team_full_name>Pittsburgh Steelers</editorial_team_full_name>
    <editorial_team_abbr>Pit</editorial_team_abbr>
    <bye_weeks>
        <week>12</week>
    </bye_weeks>
    <uniform_number>83</uniform_number>
    <display_position>TE</display_position>
    <is_undroppable>0</is_undroppable>
    <position_type>O</position_type>
    <eligible_positions>
        <position>TE</position>
    </eligible_positions>
    <has_player_notes>1</has_player_notes>
    <player_stats>
        <coverage_type>week</coverage_type>
        <week>2</week>
        <stats>
            <stat>
                <stat_id>0</stat_id>
                <value>1</value>
            </stat>
            <stat>
                <stat_id>1</stat_id>
                <value>0</value>
            </stat>
            <stat>
                <stat_id>2</stat_id>
                <value>0</value>
            </stat>
            <stat>
                <stat_id>3</stat_id>
                <value>0</value>
            </stat>

            ...

            <stat>
                <stat_id>81</stat_id>
                <value>0</value>
            </stat>
        </stats>
    </player_stats>
</player>
</fantasy_content>

Thanks!

Finally figured it out, moments after posting the question. Why does that always seem to happen?

What I needed was the NameSpace argument. Instead of hardcoding it, I retrieved the namespace of the root node and assumed the namespaces of it's children were the same:

String nameSpace = root.getNamespaceURI();
// getChildElements
Element player = root.getFirstChildElement("player",nameSpace);
Element player_stats = player.getFirstChildElement("player_stats",nameSpace);

Seems like XOM should be robust enough to deal with this, but I suppose it isn't.