How to attach technical documentation in purchase order position

Hello colleagues !

I created a document info record in Document Management System , document type Q02(DelivTerms / MM-PUR), document part 000, document version 00. The document status is RE and I attached a original document . In object link I assigned a material .

My expectations is that in purchase order position the document appears as a link. I could see this funcionality in other moment but now I can't  active it.

Anybody knows how to do it ?

Thanks a lot for your comments.

Regards

Vero