How to change the texts, "Total" and "Grand Total" in the summary header for Silverlight OlapGrid?

<UserControl.Resources>
<Utils:TextConverter x:Key="textConverter"></Utils:TextConverter>
        <Style x:Key="sumCell" TargetType="syncfusion:OlapGridTemplateCell">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="syncfusion:OlapGridTemplateCell">
                        <StackPanel Background="Honeydew">
                            <TextBlock Text="{Binding Converter={StaticResource textConverter}}"/>
                        </StackPanel>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
</UserControl.Resources>
<syncfusion:OlapGrid Height="400" x:Name="olapGrid" FreezeHeaders="True" VisualStyle="Office2007Blue" OlapDataManager="{Binding OlapDataManager}" >
<syncfusion:OlapGrid.SummaryColumnStyle>
<syncfusion:OlapGridCellStyle Style="{StaticResource sumCell}"/>
</syncfusion:OlapGrid.SummaryColumnStyle>
<syncfusion:OlapGrid.SummaryRowStyle>
<syncfusion:OlapGridCellStyle Style="{StaticResource sumCell}"/>
</syncfusion:OlapGrid.SummaryRowStyle>
</syncfusion:OlapGrid>

public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            string text = null;
            PivotCellDescriptor cellinfo = value as PivotCellDescriptor;
            if (cellinfo != null && cellinfo.DoubleValue == 0.0)
            {
                switch (cellinfo.CellValue)
                {
                    case "Total":
                        text = "агульны";
                        return text;
                    case "Grand Total":
                        text = "агульны";
                        return text;
                }
            }
            else
            {
                text = cellinfo.CellValue;
            }
            return text;
        }

Public Function Convert(ByVal value As Object, ByVal targetType As Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object
        Dim text As String = Nothing
            Dim cellinfo As PivotCellDescriptor =  value as PivotCellDescriptor 
        If cellinfo <> Nothing And cellinfo.DoubleValue = 0.0 Then
            Select Case cellinfo.CellValue
                Case "Total"
                    text = "агульны"
                    Return text
                Case "Grand Total"
                    text = "агульны"
                    Return text
            End Select
        Else
            text = cellinfo.CellValue
        End If
        Return text
    End Function