Cannot pass an autonumber field from a report via an application button

Cannot pass an autonumber field from a report via an application button

I have a report for  a table, for each record there is a button which triggers an application to send a field value to a form. If I set the field to autonumber (showing in the report) I get a null value. Setting the app to get the ID works.

I really would like the autonumber field as I do not want the user to see the record ID in the report.

Any help?