Dear Fatimah,
Dspace(and DspaceCRIS) introduced the new concept of Entity. To define a link between an Author and a Publication, you need to do two things.
1 - Both Publication and Person must be one of an entity type
2 - A relation must be defined in the relations tab in one of the record.
Pls try this.
1 - Go to the research output of the person and click to edit
2 - Go the relationship tab of the record and try to add a person relation.
3 - Go to the person record.
If you succeed in this, you will be able to see the publication linked in the person page.
If you cannot pls reach out to me, so that I can check the details.
BR.
Fatih.