Can't use {vb:raw previewtext} and {vb:raw previewimage} in vbcms_content_article_pag

[vosur]

Hi all. For begin sorry for my bad English. Sorry if I'm bad looking on the forum and not found the answer.
I need help and I would be very grateful if you help me
My problem:
I want to place social media buttons under each article in the CMS.
Have a script which is able to do:

<div class="share42init" data-url="{vb:raw page_url}" data-title="{vb:raw title}"></div>

It works and I want to add data-description="{vb:raw previewtext}" and data-image="{vb:raw previewimage}", but it's not working. How do I add these variables through the addition of modules in the template vbcms_content_article_page

In the forum http://www.vbulletin.com/ I got this advice:

Originally Posted by Wayne Luke

If a variable is not available, then you would need custom coding to register it and make it available. You can get help with custom coding at www.vbulletin.org.

Please help. Thanks