use XML::LibXML ;

my $xml = q{<?xml version="1.0" encoding="iso-8859-1"?>
<Tag1 xmlns="wow">
  <Foo>content</Foo>
</Tag1>
};

my $xml2 = q{<?xml version="1.0" encoding="iso-8859-1"?>
<Tag1>
  <Foo>content</Foo>
</Tag1>
};

my $parser =  XML::LibXML->new();
my $doc1 = $parser->parse_string($xml);
my ($foo) = $doc1->findnodes('/Tag1/Foo');

print "Foo in xml: ".$foo."\n"; ## Gives undef (with xmlns)

my $doc2 = $parser->parse_string($xml2);
my ($foo2) = $doc2->findnodes('/Tag1/Foo'); ## IS OK (without xmlns)
print "Foo in xml2: ".$foo2->textContent()."\n" ;