Php – Fatal error: Class ‘ZipArchive’ not found in

I have a problem that I install 'Archive_Zip 0.1.1' on Linux server, but when I try to run the script to create the zip file it gives the fatal error

Fatal error: Class ZipArchive not found in …

where I put the code

$zip = new ZipArchive;
var_dump($zip);
$res = $zip->open($filename, ZipArchive::OVERWRITE);
if ($res !== TRUE) {
    echo 'Error: Unable to create zip file';
    exit;
}
if (is_file($src)) {
    $zip->addFile($src);
} else {
    // echo "<br>" . dirname(__FILE__) . $src;//'/install1';
    if (!is_dir($src)) {
         $zip->close();
         @unlink($filename);
         echo 'Error: File not found';
         exit;
    }
    recurse_zip($src, $zip, $path_length);
}
$zip->close();
echo "<br>file name ".$filename;

but it doesn't find the class file.

Please tell me the solution. What should I do to resolve the problem?
I also put php.ini file to the folder where script is, but it does not work.