Master slider and thumbs

I try to fix an issue but could not manage. It is an error with the element {{thumb}} and special signs {{…}}: Failed to load resource: the server responded with a status of 404. What is wrong with the code as it should be without an error. As I understand I have put {literal} in the correct way. It is strange they use characters reserved for a server-side programming.

When I set Flickr API and connect image to the gallery, it will be an error with the thumb images:

{literal}
<img src="style/blank.gif" data-src="{{image}}" alt="{{title}}"/>
<img class="ms-thumb" src="{{thumb}}" alt="{{title}}"/>
{/literal}

{literal}
{{title}}<br />
{{description}}<br />
by:{{owner-name}} <br />
{/literal}

Is this PHP? Do you have any way to see what values are being substituted for all the tokens surrounded by {{ marks? If you right-click in the browser and view source, does that give any idea of why the 404 is happening?

I have checked an error 404. It shows up

https://www.example.com/%7B%7Bthumb%7D%7D:1

HTML translation: https://www.example.com/{{thumb}}:1

That suggests that whatever is supposed to substitute the actual parameter names (those in the {{ and }}) is not doing so.

Do you know how to eliminate those error as it seems Flickr images are not connected to the web application. Is this Flickr images as URL’s are not detected for thumb elements?