GetBindingExpression always returns null

[Patrick]

I have a column

       <telerik:GridViewDataColumn

                    UniqueName="CarrierCommission"

                                  DataFormatString="c"

                                  IsVisible="{Binding Path=SearchCriteria, Converter={StaticResource CarrierColumnConverter}}"

                                  Header="{StaticResource CarrierCommission}"

                                  DataMemberBinding="{Binding Path=CarrierRepCommission}"

                                  Width="{StaticResource CommissionColumnWidth}">

        </telerik:GridViewDataColumn>

I would like to programmatically refresh the IsVisible property by calling UpdateTarget on the IsVisible binding expression.  However, it seems that no matter when I call

 

Dim exp As BindingExpression = column.GetBindingExpression(Telerik.Windows.Controls.GridViewDataColumn.IsVisibleProperty)

I always get null for the value of exp.  When is it safe to call GetBindingExpression or is there another way to refresh the binding.

Thanks,