Events+ clients can't register - Crome and explorer

Clients are having trouble registering for the classes I installed with events+

Facebook app is integrated, and the event is open

It seams to work fun on a Mac, using Firefox, signing in with Facebook, or in an iPhone. But anyone using a Crome or explorer are having problems.

They have to press "I'm attending" a bunch of times before it registers... But often it does not register.

This needs to be an easy process, please help. Is there a way that people can just sign up with an email address them self?

When I try to apply a clients email address using the rsvp in the event (dashboard side) I get a bunch of warnings and it doesn't take.

Thanks for your help.