accidentals disappear

[Calvin Mitcham]

i'm new to lilypond, but it's working great to put in my violin lesson stuff, 
and get midi output that rosegarden then plays at the very slow tempo i need. 
now i'm wanting it to print out "large print" sheet music, that would be great. 
if i add a 
#(set-global-staff-size 28), some sharp signs disappear. a search of the list 
archive turned up nothing, anyone have a solution?

thanks in advance.
calvin mitcham