Add Items to Binding Source Problem during RUNTIME??

How in this world can I override the Bindingcontext of a combobox to add Items
at a specific position so that I can display other items beside whats in the source table

My problem is..
- I set the databindings of the combobox during design
- In form load, I add items either in combobox or binding source using add and insert method
- Unfortunately invalidOperationexception Occurs when I deploy the application

-how can I resolved this.

I USE VB.NET 2005/ CF 2.0