VisioList has its own screenshot rendering system. In order to use our screenshots you need to first request an API key http://api.visiolist.com.
Once your key has been approved you will receive an email confirming your key is active. Take that key and paste it into your admin panel -> settings
Screenshots are generate on demand and are NOT automatic. From your admin panel -> Tools -> Screenshots you can generate all screenshots for all of your members.
You can also generate individual screenshots from admin -> manage members
Users can login to their user control panel and request a new screenshot if they have made changes to their site.
Screenshots are rendered at 1000px wide, then copied to your server and resized to smaller sizes for use in ranking tables and details pages.
If your screenshots are black - make sure you are using a valid API key, and that your server has CURL enabled.