document title column in *.sdltm

I'm trying to add a column in my TMs that will show me the titles of the source documents in the Results windows. 

In addition to regular-old TMs (those created while translating), I have TMs that consist solely of "bitext" documents.  

I've followed the instructions I´ve found for modifying Settings (Fields, add a document (or x-document or DocmentTitle) row), but I cannot get a a Document Name column to appear

Thanks for any help! 

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