Page not indexable because canonical url

-- url of the page with the problem -- : horizonteaps.com.ar
-- HikaShop version -- :HikaShop [1312231536]
-- Joomla version -- : 3.1
-- PHP version -- : x.x.x
-- Browser(s) name and version -- : XXXXX x.x.x
-- Error-message(debug-mod must be tuned on) -- : Error_message

Hi,

I'm still working on SEO actions and I'm using a tool to check my site's ranking among search engines.
This tools is giving the following error: this page is not indexable. This page has a canonical url set to www.horizonteaps.com.ar/curso/curso/6-pl...l-participativa.html .

The canonical url field in the product settings is blank.
What could this be?
I'm attahcing a prtscreen of the SEO tool so you can check the whole message

Thanks!