Cross noteheads

[Andrew Neil]

When I attempt to override the notehead style to cross, I get the following output in the console:

Parsing...<unnamed port>: In _expression_ ’style:

<unnamed port>: Unbound variable: ’style

Lilypond doesn't get any further than this, and stops working.  This occurs when the following is present in my .ly file:

c4 d 

\override NoteHead #’style = #’cross 

e f 

\revert NoteHead #’style 

(As copied from section 8.4.5 of the documentation)

If I remove the \override and \revert statements, the file is parsed without a problem.  

Can anyone help?

Thanks