Hi. The previous user was running an old version at the time, but I suspect you're running the latest v2.5.252?
The current version requires a simple text file with a name on each line, with no quotes, and in standard Windows text file format with a RETURN and LF character at the end of each line. Opening in Notepad, it should look something like this:
HOMER
LISA
BART
Names can be FQDN, but most use NetBIOS names. We're actually working on a new version that will include exploring OUs within NEWT itself, so there won't be a need to import. This will be a free upgrade of course.
If you're still having problems, please let us know.