\markuplines not working under Windows

[Micah Walter]

Hello,

I'm trying to use the \markuplines command in my document.
It runs fine on my Mac, but I get the following error
on a Windows machine:

error: unknown escaped string: `\markuplines'

\markuplines \justified-lines { The entire piece can be played

The same error happens for \justified-lines, but only out of context:

error: unknown escaped string: `\justified-lines'
\markuplines 
             \justified-lines { The entire piece can be played