Magento: Using APC leads to SimpleXML PHP error

I want to use APC with Magento. I added the folling code in app/etc/local.xml:

<cache>
    <backend>apc</backend>
    <prefix>MAGE_</prefix>
</cache>

but I am getting the error below. APC is already enabled on the server and working with other sites.

The error message

Warning: simplexml_load_file() [function.simplexml-load-file]: Entity: line 58: parser error : expected '>' in /var/www/html/webkul/magento/partner/app/Mage.php on line 645

Warning: simplexml_load_file() [function.simplexml-load-file]: in /var/www/html/webkul/magento/partner/app/Mage.php on line 645

Warning: simplexml_load_file() [function.simplexml-load-file]: ^ in /var/www/html/webkul/magento/partner/app/Mage.php on line 645

Notice: Trying to get property of non-object in /var/www/html/webkul/magento/partner/app/Mage.php on line 647

Notice: Trying to get property of non-o开发者_Go百科bject in /var/www/html/webkul/magento/partner/app/Mage.php on line 647

Notice: Trying to get property of non-object in /var/www/html/webkul/magento/partner/app/Mage.php on line 647

What could lead to this error?

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I'm use memcache to provider back cache that magento can not read config file please makesure you config is correct BTW:apc is not compatible X64 OS

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Make sure your LAMP stack has all of the requirements being met:

http://www.magentocommerce.com/knowledge-base/entry/how-do-i-know-if-my-server-is-compatible-with-magento

Particularly SimpleXML.