Memcache ::不使用键数组

I am trying to test the multi_get functionality of memcached client in PHP, and I know that

array Memcache::get ( array $keys [, array &$flags ] )

is available.

00000001 <?php
00000002     function rand01()
00000003     {   // auxiliary function
00000004          // returns random number with flat distribution from 0 to 1
00000005         return (float)rand()/(float)getrandmax();
00000006     }
00000007     ini_set('display_errors', 1);
00000008     $mc=new Memcached();
00000009     $mc->setOption(Memcached::OPT_DISTRIBUTION,Memcached::DISTRIBUTION_CONSISTENT);
00000010     $mc->setOption(Memcached::OPT_REMOVE_FAILED_SERVERS,true);
00000011     echo "return value of addServer<br>";
00000012     var_dump($mc->addServer("mc1",11211));
00000013     var_dump($mc->addServer("mc2",11211));
00000014     var_dump($mc->addServer("mc3",11211));
00000015     echo "<br>";
00000016     $mc->set('00010111222',"testval");
00000017     $mc->set('00010333444',"testval");
00000018     echo "<br>";
00000019     var_dump($mc->get(array('00010111222', '00010333444')));
00000020     var_dump($mc->getResultCode());
00000023 ?>

But it gives me the following output:

   return value of addServer
   bool(true) bool(true) bool(true)
   Warning: Memcached::get() expects parameter 1 to be string, array given in /var/www/html/memcache.php on line 19
   NULL int(0)

Which means that the servers are successfully added, but get() in line 19 gives a warning for parameter being an array and the returned object is NULL. The return code is 0 which means that query was successful, and keys are present in memcached since I am setting them in line 16 and 17. Is there something I am doing wrong or is this a bug in PHP::Memcache?