XML : How to get the content from an compressed XML string Not from compress file, its string

i have query regarding gzuncompression function. first read this sentence:

To get the uncompressed XML response, the text should be decoded using Base64 first and then unzipped using GZIP libraries.

according to it i made this script:

  ==================================================  $compresskey =     'H4sIAJymPFAAA7PxD3GMd8ws8skvd0ssSg1OTSxKzggK1rfjAgAcoRiLGgAAAA==';  $uncompressData = gzuncompress(base64_decode($compresskey));  $xml=simplexml_load_string($uncompressData) or die("Error: Cannot create object");  echo "uncompressData: "; print_r($xml); exit;    ==================================================    

but it's not working. kindly help. regards