campaign custom screen

I'm having some difficulty getting my campaign custom screen to work.  Does anyone out there have an example they'd like to share.

In the documentation it says

The data source (either SQL statement or Stored Procedure) must have one and only one retrieval argument, representing the Constituent ID (customer_no) in the case of Constituent custom screens and the Inventory Number in the case of all other screens.

I'm assuming for campaign custom screens the retrieval argument should be campaign_no?

Any help would be appreciated.

Thanks,
Dale