PHP - 无法打开流：权限被拒绝

I am trying to unzip a file that is located at C:/Documents and Settings/scorpio1/My Documents/Downloads/cmsnew.zip and want to extract contents to C:\wamp\www. but the folder that will be extracted is already existed. I want that if that folder already exists, it should be replaced by the folder created after unzipping. I am getting this error.

Warning: ZipArchive::extractTo(C:/wamp/www//cmsFinalUpdate\admin\images/Thumbs.db): failed to open stream: Permission denied in C:\wamp\www\cmsFinalUpdate\extract_and_move.php

My code snippet is:

<?php
    //Step 01
    $zip = new ZipArchive();
    if ($zip->open('C:/Documents and Settings/scorpio1/My Documents/Downloads/cmsnew.zip')=== TRUE) {
        $zip->extractTo('C:/wamp/www/');
        $zip->close();
        echo "file extracted";
    }
    else
    {
        echo "Try Again";
    }
?>