Good Afternoon!

I have a xamDataGrid that looks similar to below.  As the user selects Detail Types on the page, I programmatically add an unbound field for each Detail Type to the data grid.  In the example below, the user has two detail types selected (ABC and DEF).

                                       Detail Type:  ABC           DetailType:  DEF              

Interval Ending                  Value                            Value                      Hidden Column

5/1/2013 01:00:00            5                                  4                            DetailTypes (0=ABC, 1=DEF)

5/1/2013 02:00:00            4                                  4                            DetailTypes (0=ABC, 1=DEF)

5/1/2013 03:00:00            5                                  3                            DetailTypes (0=ABC, 1=DEF)

                                       Field.Tag = 0                 Field.Tag = 1      

When adding the unbound fields, I am binding directly to the property in my entity that is displayed.

  .BindingPath = New PropertyPath("DetailTypes[" & loop & "].Value")

I am also setting the unbound field's tag property to its index in the collection.

  .Tag = loop

When formatting the Value cells, I need to access quite a few other properties that exist in the original entity, besides Value.  So I created a hidden field that is bound to my DetailTypes collection referenced above.  It exists in Record.Cells[2].

<Style x:Key="BaseValueFieldStyle" TargetType="{x:Type igDP:CellValuePresenter}" BasedOn="{StaticResource {x:Type igDP:CellValuePresenter}}" >

   <Setter Property="Background" Value="{Binding Record.Cells[2].Value[0].Difference, RelativeSource={RelativeSource Self}, Converter={StaticResource Test}}" />

   <Setter Property="ContentTemplate">

      <Setter.Value>

         <DataTemplate>

            <igWindows:CardPanel>

               <TextBlock HorizontalAlignment="Right">

                  <TextBlock.Text>

                    <Binding Path="Record.Cells[2].Value[0].Value" RelativeSource="{RelativeSource AncestorType={x:Type igDP:CellValuePresenter}}" />

                  </TextBlock.Text>

               </TextBlock>

            </igWindows:CardPanel>

         </DataTemplate>

       </Setter.Value>

    </Setter>

</Style>

Currently I have 0 hard-coded in my binding path on my styles.  The code works, and it binds to the Value and Difference properties on the first entity in my collection (Detail Type:  ABC).  Is there any way to replace the 0 in my binding dynamically with the index that exists in Field.Tag?  I have tried quite a few things with no luck.

 Thanks in advance!