Yes I use wp, and all metas are save on yoast plugin. I put my metas on yoast plugin but my snippets don't show on SERP . If you check my website - APPTUNIX(. )COMAre you using WP? You have to save your meta description before you hit the Publish button. If you have already published the article without putting the "snippet," Google would assign the first lines of the content. If the first lines are blank or just pictures, then that's what you get - blanks.
Phoebe
How i set my metas by using imoYou mean your meta description? Google won't always display your meta description if they think they can come up with something more relevant. IMO, just set up your meta tags and move on with your life.