External Data Mapping shows many link fields as unavailable

[TheBrenda]

Re: External Data Mapping shows many link fields as unavailable

User has an external excel file. They are doing an External Data Mapping, selects an Existing Query Subject and many of the fields have a red circle with a white X, meaning that those fields are not available to select for a New Link. I have looked at the definition of the fields that are available and those that are not and cannot find a definitive pattern. It might have something to do with if the fields are in a seperate table that is used in a join? But not sure. Any ideas?