Why does my property always say that it has no availability for the chosen dates?

I am confused. I have set my calendar up correctly, and received a few bookings over the last month or so. BUT, it is very sporadic of late and looking into it in more detail, as I go on to Booking.com as a member of joe public, I cannot book my apartment for love nor money! It always says to me that it is unavailable on the chosen dates. 

My calendar says I have availability on those chosen dates, so I cannot see why it is showing the public that they cannot book?? 
I have checked my restrictions, and again I cannot see anything that would prevent a booking.