This is where the form and report objects differ (for no reason that I can think of). In a form, you can reference ANY field in the form's RecordSource in VBA. In a report, you seem to need to add a control (hidden is fine) in order to reference a field.
In either case, if your control has a different name from its ControlSource column name, you will see both names in the intellisense list. For both forms and reports so I don't know why reports work differently.
If you are having trouble with the code not "seeing" the field, try deleting the form's RecordSource and then replacing it. This makes the form/report refresh its fields collection which is sometimes necessary if you added the column to the recordSource after you originally created the form/report.