Denials of registrants for webinar

Last week, our organization held a webinar, and I was pleased to see 71 registrants. However, when I downloaded the list, only 65 registrants had been "approved". I know I did not deny any registrants, so how did this happen? 

Also, I noticed that some who had been denied actually did attend, so what happened there?

I want to prevent this from happening in future webinars, so please help me understand.

Thank you, 

Heidi Whitman

National Association of District Export Councils