Hello Thomas,

Thank you for using Infragistics components.

By design, the background color of AlternateRecords in Theme Office2013 is set to #FFFFFF (white) and that's the reason you couldn't see difference. My suggestion to achieve your requirement is to change the default style of the DataRecordCellArea and to set values for BackgroundAlternate and BorderAlternateBrush properties there.
For example:

 <igWPF:XamDataGrid.Resources>
                <Style TargetType="{x:Type igWPF:DataRecordCellArea}">                  
                    <Setter Property="BackgroundAlternate" Value="#E6DBDF" />
                    <Setter Property="BorderAlternateBrush" Value="#E6DBDF" />
                </Style>
 </igWPF:XamDataGrid.Resources>

I have attached a sample application, that uses the approach from above.

If you require any further assistance on the matter, please let me know.

Sincerely,
Teodosia Hristodorova
Associate Software Developer
Infragistics