The column used by relationship is missing... how to add?

I am trying to uplift a Crystal Report to E10. When I run the report I get the error “The column PartPlant.Plant used by the ‘PrimBin’ relationship is missing. Include the column or remove the relationship.”

When I open the report in SAP Crystal Reports 2013, I can see that it indeed is missing. In the Field Explorer, under Database Fields I see the PartPlant table, and there is no Plant field. However, I am unclear as to how to get this field added. In the past, I am used to going to the database menu and using “Set Datasource Location” and then opening the XML file from the report I tried to print and then finding the field there. (I have always found that process confusing.) But in any case, there is no XML file in this case. There is an XML file from a different style of the report, but it doesn’t have the missing field.

How do I add this field back to the report so that it will run?