readonly fields not updating

Hello,

I am using jscalendar to allow the user to select a date and populating
a readonly text field with the value. When I update the record the
value does not persist. If I change the text field to editable the
value saves fine. I am using the jscalendar to update the field the
same way in both instances.

Is there clean way to force the update?

Thanks,
Dan