Problem with Installation (SimpleXML)

Hi,

I still have problem installing OP. I get the following:

Requirements problem
The following error must be resolved before you can continue the installation process:
More Like This Yahoo! BOSS module requires the PHP SimpleXML extension.

But when I check my PHP info it says that Simple XML is enable.

PHP Version 5.2.11

memory_limit 128M
max_execution_time 180
realpath_cache_size 2M

Simplexml support enabled
Revision $Revision: 272374 $
Schema support enabled

I usually have no problem installing Drupal, but seems not to work with OP.

Thank you in advance for your help.