my code is 

<igDP:XamDataGrid Name="xamDataGrid" SelectedDataItemsScope="RecordsOrCells" RecordContainerGenerationMode="Virtualize"
DataSource="{Binding CallEventFilterLogFilesDataList, UpdateSourceTrigger=PropertyChanged}" SelectedDataItems="{Binding SelectedItems, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" GroupByAreaLocation="None"
>
<igDP:XamDataGrid.Resources>


</igDP:XamDataGrid.Resources>
<igDP:XamDataGrid.FieldLayoutSettings>
<igDP:FieldLayoutSettings AllowFieldMoving="WithinLogicalRow" AutoGenerateFields="False" AllowDelete="False" DataErrorDisplayMode="Highlight" SupportDataErrorInfo="RecordsAndCells"/>
</igDP:XamDataGrid.FieldLayoutSettings>
<igDP:XamDataGrid.FieldSettings>
<igDP:FieldSettings AllowSorting="False" CellClickAction="SelectRecord" DataItemUpdateTrigger="OnCellValueChange"/>
</igDP:XamDataGrid.FieldSettings>
<igDP:XamDataGrid.FieldLayouts>
<igDP:FieldLayout>
<igDP:FieldLayout.Fields>
<igDP:DateTimeField Width="0.35*" Mask="yyyy/mm/dd hh:mm:ss" Format="yyyy/MM/dd HH:mm:ss" Name="StartDateTime" Label="StartTime" AllowEdit="True" AllowDropDown="False">

</igDP:DateTimeField>
<igDP:DateTimeField Width="0.35*" Mask="yyyy/mm/dd hh:mm:ss" Format="yyyy/MM/dd HH:mm:ss" Name="EndDateTime" Label="EndTime" AllowEdit="True" AllowDropDown="False"/>

</igDP:FieldLayout.Fields>
</igDP:FieldLayout>
</igDP:XamDataGrid.FieldLayouts>
</igDP:XamDataGrid>

i have binded the start and end time with the columns and i got the value in the columns in the form of milliseconds too but when i double click on it for editing it showing fff instead of milliseconds, it should display milliseconds