Correct FB pic not populating

Hi. For my site www.denverdispensaries.net I have installed your plugin and created an app to get the app id. I have then put in the default image into the settings, yet when I post the URL on Facebook it does not grab the default image for the home page. Can you please advise?

Thanks so much

https://wordpress.org/plugins/wp-facebook-open-graph-protocol/