Silverlight DataPager control loses first/last buttons

I'm using the DataPager control in XAML as follows:

     <Grid.ColumnDefinitions>
      <ColumnDefinition Width="1*" />
      <ColumnDefinition Width="1*" />
      <ColumnDefinition Width="1*" />
     </Grid.ColumnDefinitions>

    <data:DataPager Grid.Column="1"
       Source="{Binding PagedCollection, ElementName=开发者_JAVA技巧ucPagingControl}"
       PageSize="{Binding PagedCollection.PageSize, ElementName=ucPagingControl}" 
       AutoEllipsis="True" 
       DisplayMode="FirstLastPreviousNextNumeric" />

and all displays well for the first 99 pages

However, after page 100 I lose the first/last button graphics

Any ideas why or how to change the number of pages displayed to recover the space?

---

Turns out the fix was in the Grid definition. The following works:

     <Grid.ColumnDefinitions>
      <ColumnDefinition />
      <ColumnDefinition Width="Auto" />
      <ColumnDefinition />
     </Grid.ColumnDefinitions>