Advanced custom field thumbnail not showing

I’m using Advanced custom fields plugin to embed vine videos on my site, it doesn’t fetch the thumbs, here is the code:

<iframe src="https://vine.co/v/<?php the_field('vine_video_link'); ?>/embed/simple?audio=1" width="540" height="540" frameborder="0"></iframe>

Thanks in anticipation.

https://wordpress.org/plugins/video-thumbnails/