During reservation procedure, the first time that i select month squares are ok but
when i change selected month squares dissapear from my selection and i can't make a reservation....

Hello,

You need to make reservation starting in one month and ending in another month? It should be possible and it works for me. Select start day, change month and select end date. It should not refresh page, but enlarge your calendar with more months. Tested with Book it! 2 beta4 and Joomla 3.0.