How to set value for MiniDateRangeItem

Hi,

I try to set the value for MiniDateRangeItem from code as follows:

MiniDateRangeItem mdri = new MiniDateRangeItem();
DateRange = new DateRange();
dateRange.setRelativeStartDate(new RelativeDate("-1200m"));
dateRange.setRelativeEndDate(new RelativeDate("-1000m"));
mdri.setValue(dateRange);

But the value is not getting displayed in the field.

Thanks,
Ramya