Reading XML and newbie PHP help

[Anon]

I don't know why but I thought I would try and learn a little PHP. So I thought I would try to build a text based link bar along the left hand side of the screen by reading an XML file such as:

Main
Home
News
My Stuff
One
Two

I made two classes but I can't seem to get past an error saying I am calling a method of
a non object or something. I am not sure what the rules are for posting code here, but in the code below I get an error trying to call $tmpLinkBarItem->setProperty( ... );

The error says "Call to a member function on a non-object on line 112"

What I thought was strange was I could rem out either the call to setProperty or the line before it where I extract an object out of the array, I don't get the error. I don't get any results either, but still no error. Could I be looking in the wrong place?

Now granted my sytanx may not be great nor my classes purpose very well defined but I am new to this PHP stuff.

<?php

class TLinkBarGroup
{
var $Items = array();
var $ItemCount = 0;
var $Name = '';
}

class TLinkBarItem
{
var $ItemName = '';
var $ItemTarget = '';
var $ItemLink = '';

function setProperty( $AProperty, $AValue )
{
  switch ($AProperty)
  {
    case "ITEMNAME":
	  $this->ItemName = $AValue;
	  Break;
	case "ITEMTARGET":
	  $this->ItemTarget = $AValue;
	  Break;
	case "ITEMLINK":
	  $this->ItemLink = $AValue;
	  Break;
  }
}

function GetProperty( $AProperty, $AValue )
{
  switch ($AProperty)
  {
    case "ITEMNAME":
	  return $this->ItemName;
	  Break;
	case "ITEMTARGET":
	  return $this->ItemTarget;
	  Break;
	case "ITEMLINK":
	  return $this->ItemLink;
	  Break;
  }
}

}

function GetLinkBarItems( $ALinkBarXMLFilePath )
{
$GroupData = array();
$GroupCount = 0;
$xml_current_tag_state = '';
$CurrentGroup = new TLinkBarGroup;

if( !($fp = fopen( "assets/xml/linkbargroups.xml", "r" )) )
  die( "Couldn't open xml file (assets/xml/linkbargroups.xml)" );


function StartElementHandler( $Parser, $ElementName, $ElementAttributes )
{
  global $GroupCount;
  global $GroupData;
  global $xml_current_tag_state;

  $xml_current_tag_state = $ElementName;
}  

function EndElementHandler( $Parser, $ElementName )
{
  global $GroupCount;
  global $GroupData;
  global $xml_current_tag_state;
  global $CurrentGroup;

  if( $ElementName == "GROUP" )
    $GroupCount++;  

  if( $ElementName == "ITEM" ) 
    $CurrentGroup->ItemCount++;

  $xml_current_tag_state = '';
}

function CharacterDataHandler( $Parser, $Data )
{
  global $GroupCount;
  global $GroupData;
  global $xml_current_tag_state;
  global $CurrentGroup;
  $tmpLinkBarItem = new TLinkBarItem;

  if( $xml_current_tag_state == '' )
    Return;

  if( $xml_current_tag_state == "GROUPNAME" )
    $CurrentGroup->Name = $Data;

  if( ($xml_current_tag_state == "ITEMNAME") or 
      ($xml_current_tag_state == "ITEMTARGET") or  
	  ($xml_current_tag_state == "ITEMLINK") )
  {
    $tmpLinkBarItem = $CurrentGroup->Items[$CurrentGroup->ItemCount];
	$tmpLinkBarItem->setProperty( $xml_current_tag_state, $Data );
  }
}


if( !($XMLParser = xml_parser_create()) )
  die("Couldn't create xml parser (linkbaritems)");

xml_set_element_handler( $XMLParser, "StartElementHandler", "EndElementHandler" );
xml_set_character_data_handler( $XMLParser, "CharacterDataHandler" );

while( $Buffer = fread( $fp, 4096 ) )
{
  if( !xml_parse($XMLParser, $Buffer, feof($fp)) )
  {
    break;
  }
}

xml_parser_free( $XMLParser );

return $GroupData;

}

?>