Does anyone see an issue with this Twitter Card code? The validator fails and says ERROR: Card validation failed with the reason that hopconferences.com is not whitelisted? What is whitelisted mean and how do I ensure that my site is?
<meta name="twitter:card" content="Hope Conferences presents The Reason For Our Hope, a Catholic Conference. September 30, 2017 at the Lowell Memorial Auditorium." />
<meta name="twitter:title" content="Hope Conferences - The Reason For Our Hope" />
<meta name="twitter:description" content="Catholic conference featuring great speakers" />
<meta name="twitter:url" content="http://www.hopeconferences.com" />
<meta name="twitter:image" content="http://www.hopeconferences.com/images/twitter-image.jpg" />