I am adding a cd "guitar improvisation for dummy"(in french)
There are 96 tracks, and most are juste
"Example xx.a-b" to say that it's chapter xx, example a to b of the book.
There were a few, which were "Example 15.7" and I guess that Musicbrainz thought that it was a lenght, because I received this error message

Error: Track 96 has an invalid length. Must be in the format MM:SS

I have no idea what to do, I can't edit it in basic mode
And in advenced mode, I can edit author, add credits, change the title... but I can't change the length anymore, it's always 15.7

I have no clue what to do to submit the cd, or tell music brainz that I didn't want to add any length