Friends/relatives ignoring invitation

Maybe I'm being too sensitive but it's a month until my wedding, which will be followed by a catered BBQ the next day. A couple of relatives have not responded at all, but we found out through others that they won't be attending. We did an online evite for the bbq, which lets us see who has viewed the evite and when. About 10 people have totally ignored the evite. About half a dozen others have viewed it but not indicated whether they are coming or not. I guess that means they aren't coming, but it's so aggravating to invite people who don't even bother to click through or have the courtesy to inform us that they won't be coming. It feels like planning a wedding really shows who are really your friends. You see who is truly excited about your wedding and is supportive. Meanwhile, I see some of these people active on facebook, so I know they're checking email and online pretty much everyday. Just wanting to vent. Thanks for listening.