Trouble with VLookup

Column A is a defined list of Login Names, Column B is a VLookup which looks at a table of Login Names and Display Names

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When I select a login in Column A, it auto-populates the display name as expected and returns the error text "ERROR" if there is no display name. This is as expected.

If I flip that, however, and create a defined list of Display Names in Column D and the VLookup (looking at the same table) in column E to return Login names, every result is an Error unless the Display and Login Names are exact matches.

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If I change "FALSE" to "TRUE" it stops returning the error text, but the results are also incorrect...

I am wracking my brain trying to figure out why and coming up empty. Can anyone help explain why this is happening? (Example Spreadsheet attached.