Magento – magento session and memcache issue

I used memcached for sessions, but when I click on the website, got error for session_start

error is :

PHP Fatal error:  session_start(): Failed to initialize storage module: memcache (path: /var/lib/php/session) in /var/www/html/mydomain.com/app/code/core/Mage/Core/Model/Session/Abstract/Varien.php on line 125

This is my local.xml

<session_save><![CDATA[memcache]]></session_save>
<session_save_path><![CDATA[tcp://localhost:11211?persistent=1&weight=2&timeout=10&retry_interval=10]]></session_save_path>

also this is my memcache result

[root@www ~]# ps ax | grep memcache
19842 ?        Ssl    0:00 memcached -d -p 11211 -u memcached -m 64 -c 5024 -P /var/run/memcached/memcached.pid -l 127.0.0.1
20734 pts/0    S+     0:00 grep memcache

and ports

[root@www ~]# netstat -tulpn | grep :11211
tcp        0      0 127.0.0.1:11211             0.0.0.0:*                   LISTEN      19842/memcached
udp        0      0 127.0.0.1:11211             0.0.0.0:*                               19842/memcached

what is wrong here for memcache config ?