Line breaks not working despite using \break

[Robert Blackstone]

Hi all, 

I’m presently struggling with a keyboard score and I know exactly where line 
breaks have to be inserted to make the score readable.
So I enter \break at those points, in all voices, but it does not work at all.
The result is a cluttered, ugly and  for the pianist practically unreadable 
score. 

Does any of you know another way to force a line break?
I’m using TeXShop on my Mac. Usually  "\break" works perfectly.

Thanks in advance for any advice.

Best regards,
Robert Blackstone