Even without specifying format, there is a bug. I'm just using:
<cool:DatePicker ID="DatePickerMapDate" runat="server" />
And on each post back the days and month swaps (i.e. I put 01/03/08 and after a postback the date changes to 03/01/08). Furthermore, I can never select a day > than 12 otherwise I get:
[FormatException: String was not recognized as a valid DateTime.]
System.DateTimeParse.Parse(String s, DateTimeFormatInfo dtfi, DateTimeStyles styles) +2273210
System.DateTime.Parse(String s) +22
Coolite.Web.UI.DatePicker.get_SelectedDate() +110
Coolite.Web.UI.DatePicker.LoadPostData(String postDataKey, NameValueCollection postCollection) +170
Coolite.Web.UI.Field.System.Web.UI.IPostBackDataHandler.LoadPostData(String postDataKey, NameValueCollection postCollection) +11
System.Web.UI.Page.ProcessPostData(NameValueCollection postData, Boolean fBeforeLoad) +661
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1194
I think this is related to the swaping day/month.
Another bug is that when it's inside an UpdatePanel, on postbacks, there's a duplicate calendar icon for the calendar textbox (both icons are functional; the duplicate icon appears at the begining of the textbox, hiding the day)