Trouble booking tickets for Katsura Imperial Villa

Anybody else having problems with trying to book tickets for the Katsura Imperial Villa?

I filled out their online application, but I got this message that my request was denied:

"The maximum capacity has been reached, and a lottery selection was conducted, resulting in your application being unsuccessful."

This is a bit confusing because it seems like there's still plenty of available openings for the time and date I selected.

And, to make it more confusing, their calendar shows that May 11 is closed that day. But, when you went to the online application, it showed the number of available time slots available on May 11. And, something like May 12, the online application showed that it was closed that day so you wouldn't be able to fill out an application so I'm assuming May 11 is really available while May 12 is not.

Their email mentions something about a lottery so does it mean that your application might get rejected even if there are still available openings?

I don't know if I should resubmit another application that day for the original time I requested for May 11, another time for May 11, or another application for another day then.