求救，怎么使用php读取word页数？？报错

<?php 

$word = new COM("word.application") or die("Unable to instantiate Word");
echo "Loading Word, v. {$word->Version}";
$word->Visible = 0;
$word->Documents->Open( "D:\\2.doc" );
$test= $word->ActiveDocument->content->Text;
echo $test;
//$word->Documents->Open( "D:\\1.doc" );
$num_pages = $word->ActiveDocument->ComputeStatistics($wdStatisticPages);
echo "-----------------".$num_pages;
?