Telerik ComboGrid控件上的TabIndex无法通过数字序列正常工作

Question

我给每个控件提供Tabindex值，但是在combogrid上它没有正确的序列。就像我将数字'0'给予combogrid但是在tabnavigation上它最终选择。它实际上以1,2,3,4,5,7,0,6,8的形式显示。所以你可以看到最后的所有comboGrids显示。

<Grid Name="grdLoanReuqest" Grid.Row="1" KeyboardNavigation.TabNavigation="Local"  KeyboardNavigation.IsTabStop="True"  >
        <Grid.RowDefinitions>
            <RowDefinition Height="27"/>
            <RowDefinition Height="27"/>
            <RowDefinition Height="27"/>
            <RowDefinition Height="27"/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="154"/>
            <ColumnDefinition Width="182"/>
            <ColumnDefinition Width="162"/>
            <ColumnDefinition Width="435" />
        </Grid.ColumnDefinitions>
        <ccWFS:ComboGrid KeyboardNavigation.TabIndex='0' KeyboardNavigation.IsTabStop="True" />
        <ccWFS:ComboBox  KeyboardNavigation.TabIndex='1' KeyboardNavigation.IsTabStop="True" />
        <ccWFS:TextBox  KeyboardNavigation.TabIndex='2' KeyboardNavigation.IsTabStop="True" />
        <ccWFS:DatePicker KeyboardNavigation.TabIndex='3' KeyboardNavigation.IsTabStop="True"/>
        <ccWFS:ComboBox KeyboardNavigation.TabIndex='4' KeyboardNavigation.IsTabStop="True" />
       <ccWFS:ComboGrid  KeyboardNavigation.TabIndex='6' KeyboardNavigation.IsTabStop="True"/>
       <ccWFS:TextBox KeyboardNavigation.TabIndex='5'   KeyboardNavigation.IsTabStop="True" />
       <ccWFS:DatePicker KeyboardNavigation.TabIndex='7'  KeyboardNavigation.IsTabStop="True" />
       <ccWFS:ComboGrid  KeyboardNavigation.TabIndex='8' KeyboardNavigation.IsTabStop="True" />
   </Grid>
</Grid>