Zend certified PHP/Magento developer

Facebook sharing debugger tells me that og:image is not specified in the page, but it is?

I had read many articles and tried different solutions, but facebook debugger still tells me: The ‘og:image’ property should be explicitly provided, even if a value can be inferred from other tags.

In the head tag, I have

<meta property=”og:image”

Other open graph attributes, like the page title and page descriptions are found properly.

I has PHP instructed to send a header no cache, and in .htaccess have also disabled caching.
I also had
but removed it (PHP line commented) after I got no changed from the FB debugger.

If I use tthe Linkedin sharing debugger (Post Inspector), the image is shown correctly.

Site is a PHP site, no wordpress, and don’t know if I can use an SEO plugin to help overcome issue.

Any help please?