Color for the center of a doughnut

Hi,

We are putting some doughnut charts to track progress on certain items. They work very well, but when the value is zero, the doughnut center takes the color of the outside.  Is there a way to keep the center white?  I can find nothing on controlling the center color.  Thanks.

Here is our definition:

<telerik:RadHtmlChart runat="server"
                    ID="RadHtmlChart1"
                    Width="100%"
                    Height="350"
                    Transitions="true"
                    Skin="Metro"
                    EnableTheming="False"
                    RenderMode="Mobile"
                    style="padding-left:30px">

                <Legend>
                    <Appearance Position="Right" Visible="false">
                    </Appearance>
                </Legend>
                <PlotArea>
                    <Series>
                        <telerik:DonutSeries StartAngle="90"  HoleSize="85" DataFieldY="dat" ColorField="color">
                        <LabelsAppearance Visible="false"> </LabelsAppearance>
                            <TooltipsAppearance Color="White" DataFormatString="{0}%"></TooltipsAppearance>
                            <SeriesItems>
                            </SeriesItems>
                        </telerik:DonutSeries>
                    </Series>
                </PlotArea>
                </telerik:RadHtmlChart>