@Roberts324
It looks like your doing everything correct. Can you validate "impbuild.exe" is working properly. Imbuild has a dependency on ePublisher.
Try this command from the command line. The only part you might have to fix is the location of "impbuild.exe"
Code:
"c:\program files\ebookutils\impbuild.exe" --out-dir="." --name="TrueNames.imp" --title="True Names" --author="Cory Doctorow" --1150 "Cory_TrueNames.html"
With the attached file (unzip the HTML file)