Set FormatString for Componentart:GridColumn from web config

Question

I have a componentart:GridColumn date column, currently it sets it FormatString like this

`

 <componentart:GridColumn DataField="DtofExpiry" HeadingText="Date Of Expiry" EditCellServerTemplateId="PickerTemplate"
                                                            FormatString="MM/dd/yyyy" Width="100" AllowEditing="True" EditControlType="Custom"
      />

`

I want to set this FormatString from the code behind. I have tried putting it like this FormatString='<%Appconfigures.ApplicationConfiguration.GetConfigurationByKey("AppDateFormat").ToString()%>' but it gives me an error Error:Databinding expressions are only supported on objects that have a DataBinding event. ComponentArt.Web.UI.GridColumn does not have a DataBinding event.