Getting a Code Snippet to Display in Column of Datagrid That is Bound to Sales Orders in SalesLogix

Question: In SalesLogix I have a datagrid that is bound to sales orders.  I am
trying to get a code snippet to display in one of the columns.  The code
snippet returns a double and looks like this:

result = 0;

The form compiles just fine but I receive this error when I try to run it:

“could not resolve property: ItemsExtendedPriceSum of: Sage.SalesLogix.Entities.