Datepicker confusion!

Datepicker confusion!

I currently have this line of code initialising a datepicker on my form:
$("#datepicker").datepicker({showOn: 'both', buttonImage: 'calendar.gif', buttonImageOnly: true, dateFormat: 'dd/mm/yy', constrainInput: true, mandatory: true, maxDate: (new Date()), showYearNavigation: false, minDate: '06/02/2010'});
For some reason, this allows the user to select all dates, where in fact it should let me choose 6-8 Feb. Interestingly, when I remove the minDate property, it allows me to select all dates up to the current one. Interestingly, the toString of the maxDate gives the same format string as the manually entered one there.

Any ideas?