Can't import tracks.

Question

Does not work, because I get "Error:Length cannot be less than zero. Parameter name: length" for all songs.

Answer 1

You have songs that you are trying to add with their name being an empty space. The software can't identify those songs if they don't have a name. I recommend you add them to a player that supports IDv3 tags to see which track lacks a name.

I recommend using Winamp for this procedure: http://www.winamp.com/index.html

Winamp can read IDv2/3 tags from a file. After you find and edit the file, load it again into the iTunes Lyrics Importer.