jquery date picker disabling field

i have a situation that the jquery date picker is disabling my date field, for some reason.

here it is on JSfiddle: http://jsfiddle.net/VFEMA/

reproduce: choose a DAY.

then choose the MONTH for the same date set.

you will see that the day has been disabled completely for some reason. it should disable only the 开发者_如何转开发options that are not relevant for that month (eg: 29,30 and 31 for Feb).

any ideas why?

I am sure this was working at some stage... thanks in advance!

In your function

function checkLinkedDays2() {}

update the line

$('#x_StartDateD option').attr('disabled', '');

to

$('#x_StartDateD option').removeProp('disabled');

BTW: Why do you use the datepicker plugin if you're creating your own solution?