Error invalid days of next month

[abertranb]

Hi! first of all thanks for your great job!!!

Then I found a little bug in calendar but i can't solve it!
When I have to calendars linked and the navigation is 1. When I select a day of the next month and then I want to open the second calendar the days are disabled.

For Example:
http://tresipunt.com/testcalendar/

Today is 28 of June

First calendar: select 4 of July
Second calendar: open calendar and all days are disabled
Configuration:
myCal1 = new Calendar({ date1: 'd/m/Y', date2: 'd/m/Y' }, { navigation: 1, offset: 0, pad: 0, direction: 1, tweak: {x: 6, y: 0} });

Thanks, in advance!!!!