Merged Requirements check:FAILED

Hi, I want to install Kunena 1.7.2 on Joomla 1.5 which is running on CentOS. However, when I tried to install it, the following message is shown:

REQUIREMENTS CHECK: FAILED - Minimum version requirements not satisfied
PHP version: 5.3.3 (Required >= 5.2.3)
MySQL version: 5.1.61 (Required >= 4.1.19)
Joomla version: 1.5.23 (Required >= 1.5.20)
PHP DOM Extension: DOMDocument (Required)

Looks like my PHP, MySQL, and Joomla version don't seem to be the problem since they're all above the requirement. But I'm curious about "DOMDocument", is it the problem that I can't install Kunena? What should I do about that?
Your help is highly appreciated...

G'day, catonakarin, and welcome to Kunena.

If I was in your situation, I would contact the people who are hosting your website and ask them about installing DOMDocument support in PHP.

Thanks for your advice, but the thing is I am the one who host that website. Could you show me more about DOMDocument and how to install it?

This is a question of webhosting. If you webhosting software does not meet the technical requirements to run Joomla or Kunena there's not a lot we can do to help you. When you say that you are the one hosting your website, what kind of webhosting software solution are you using? Is your website on the internet?

My site is running on dedicated server (CentOS). There's no Cpanel or other web hosting software in the server. I just copied the website files to "/var/www/html" directory and edit the configuration file. Previously, I developed that site on my pc running on Window 7 and used joomla 1.5. The Installation works fine. But in the dedicated server, problems occurred.

As I wrote, this is a webhosting issue. I don't know enough about those kinds of things - maybe the Joomla forum may have some tips - or perhaps another member of this community can advise you.