Over the course of the many months we've had a private blog, I've received probably a dozen emails from friends who either never got my invite, or whose invite suddenly wasn't working or had somehow expired.
These are all frustrating mysteries to me, because in my settings it appears that all is well and invites are current and working. However when I remove their invite and invite again, it works for them (at least for the time being!).
So if you have issues, please let me know!
caileankohagen at gmail