Warning: ZipArchive::close(): Invalid or uninitialized Zip object

foreach( glob($sourcedir.'*.[zZ][iI][pP]') as $zippath)
 {
  // create daily zip file
  $zipname = preg_replace('~'.$sourcedir.'~','',$zippath);
  $zipname2 = preg_replace('~.zip~','',$zipname);

  $zip = new ZipArchive();
  $ret = $zip->open($xmlzip.$zipname2.'_contact_xml.zip', ZipArchive::OVERWRITE);

  // move xml files to daily zip file created above
  if ($ret !== TRUE) {
    printf('Failed with code %d', $ret);
    } else {
    foreach(glob($source_file_path.'*.[xX][mM][lL]') as $xmlpath){
    $zip->addFile($xmlpath, preg_replace('~'.$source_file_path.'~','',$xmlpath));

   }
 }

$zip->close();

 }