I am trying to create an array that I can include the perent category Name and the child category Name. I can so far access the below object fine using $xml->Subcategories; but if I try my code below I get an empty array why?

PHP:

foreach ($catDetailsXml->Category as $value) 
        {

            $categoryDetails[] = array('CategoryNumber' => $value->Number);
        }

Structure:

object(SimpleXMLElement)#13 (1) {
  ["Category"]=>
  array(5) {
    [0]=>
    object(SimpleXMLElement)#14 (4) {
      ["Name"]=>
      string(19) "Commercial Property"
      ["Number"]=>
      string(10) "0350-0100-"
      ["Subcategories"]=>
      object(SimpleXMLElement)#35 (1) {
        ["Category"]=>
        array(3) {
          [0]=>
          object(SimpleXMLElement)#36 (4) {
            ["Name"]=>
            string(9) "Car parks"
            ["Number"]=>
            string(15) "0350-0100-8946-"
            ["Subcategories"]=>
            object(SimpleXMLElement)#39 (0) {
            }
          }