when you set the first day of week parameter to Monday, all events scheduled on a Sunday seem to get displayed either on the day before or after.
If you set the first day of week to Monday, the events are correctly displayed.
I have attached 4 screenshots.
3 of them show the calendar setup with Monday as first day of week and you can see all the events scheduled for the Sunday March 29th displayed on Saturday March 28th.
The last screenshot shows the calendar with Sunday as first day of week and all events are now correctly displayed.
You can see the calendar under this address: http://www.technolink.lu/en/leisure