How-to-convert-DataRange-type-to-start-end-date

Can you tell us what your objective is with this?

CODE:
<wpf:DataRangeDropDown Height="20" Margin="0,4,4,4" Name="cmdDataRange" Width="90"/>

Added this component to my extension GUI and want to load bar history like this

CODE:
BarHistory bars = WLHost.Instance.GetHistory(symbol, cmbSelector.SelectedHistoryScale, cmdDataRange.DataRange.StartDate, cmdDataRange.DataRange.EndDate, 0, cb);

But start and end date not representing what I have selecteed from the DataRangeDropDown
Searched for method to convert DataRange to start-end date and haven't found it.