If someone has setup an invite on the web and you are having trouble with the invitation (can't reply to it, can't invite yourself, can't invite others, ...), then PLEASE DO NOT MAIL ME ABOUT IT
I'm sorry that I have to be so harsh, but I did not setup the invitation, I know nothing about it, and I cannot help you.
I merely wrote the software that someone else is using, and I can't help the users of someone else's web page. Either email the host of the event or else find out who owns the website and talk to them.
I get hundreds of email from people about this, and I have no way to help them even if I wanted to.
Obviously if you are installing the DaVite software and you are having problems, then feel free to contact me.