Always use the non-DLL versions, i.e., POPOR04.

You can achieve your requirement by using the sub-report option, you can get the PO optional field values in your dll report. Basically you have to create sub report and attach PO optional tables in the sub-report and pass the PO Unique number to sub report as the selection criteria and display required optional field values in the sub report.

HTH

Sincerely,

Dinesh