First, there's an error in the XML. 

<MyImportantNode> xsi:type="foo" GeneralID="Random1" >

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should be 
<MyImportantNode xsi:type="foo" GeneralID="Random1" >

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(Same goes for the other two.)

4 of the 5 paths you tried in the loop start with "/". That means they start looking at the root of the tree. That instantly makes them wrong since you obviously want something that's in or below $nodeybits.

Another major problem is that you look for the nodes in the wrong namespace throughout the body of the loop. You don't even use the xpc! 

<?xml version="1.0" encoding="UTF-8"?>
<RootTag SchemaVersion="1.1" xmlns="http://www.wow.com/BlahML"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocati
+on="http://www.wow.com/BlahML BlahML1_1.xsd">

<MyTagA Tag="XXX">Some Text A</MyTagA>
<MyTagB Tag="XXX">Some Text A</MyTagB>

 <MiddleTag xsi:type="foo" magicvalue="wow">

    <MyImportantNode xsi:type="foo" GeneralID="Random1" >
        <CannotGetTagA>YYYYYYYYYYY</CannotGetTagA>
        <CannotGetTagB>ZZZZZZZZZZZ</CannotGetTagB>
    </MyImportantNode>
    <MyImportantNode xsi:type="foo" GeneralID="Random2" >
        <CannotGetTagA>YYYYYYYYYY22</CannotGetTagA>
        <CannotGetTagB>ZZZZZZZZZZ22</CannotGetTagB>
    </MyImportantNode>
    <MyImportantNode xsi:type="foo" GeneralID="Random3" >
        <CannotGetTagA>YYYYYYYYY333</CannotGetTagA>
        <CannotGetTagB>ZZZZZZZZZ333</CannotGetTagB>
    </MyImportantNode>

</MiddleTag>

</RootTag>

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use strict;
use warnings;
use feature qw( say );

use XML::LibXML;

my $parser = XML::LibXML->new();
my $doc = $parser->parse_file('test.xml');

my $xpc = XML::LibXML::XPathContext->new($doc);
$xpc->registerNs(theNS => 'http://www.wow.com/BlahML');

for my $important_node (
   $xpc->findnodes('//theNS:MiddleTag/theNS:MyImportantNode')
) {
   say $important_node->getAttribute('GeneralID');

   for my $cannot_get_a_node (
      $xpc->findnodes('theNS:CannotGetTagA', $important_node)
   ) {
      say $cannot_get_a_node->textContent();
   }
}

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In reply to Re: LibXML, Namespaces, xpath expression - This should be simple. by ikegami
in thread LibXML, Namespaces, xpath expression - This should be simple. by alittlebitdifferent

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