The RSVP is quite staunch on how it accepts names.
Try a few different ways of how your Envelope was written.
We recommend your first name or your title!
EXAMPLE: Mr. & Mrs. (Addressed Mr. & Mrs. Doe)
EXAMPLE: John (Addressed John Doe)
Please enter the first and last name of one member of your party below. If you're responding for you and a guest (or your family), you'll be able to RSVP for your entire group on the next page.