problems with chords

[Deborah Lowrey]

Dear Lilypond,

I am typesetting a small aria from Die Zauberflote. I
have already done the first two movements and had no
problems. I got to the third and have been having a
problem. Through some investigation I've found that if
I enter a chord <note note> or any variation in <> I
get the following error:

address@hidden ~/MF4-Arie$ ly2dvi -P
allegromoderato.ly
Running LilyPond...
 -I /home/Default/MF4-Arie -H dedication -H title -H
subtitle -H subsubtitle -H
footer -H head -H composer -H arranger -H instrument
-H opus -H piece -H metre -
H meter -H poet -H texttranslator -H papersize -H
textheight -H pagenumber -H la
nguage -H latexheaders -H latexoptions -H linewidth -H
latexpackages -H unit -H
orientation /home/Default/MF4-Arie/allegromoderato
GNU LilyPond 1.5.60.jcn1
Now processing:
`/home/Default/MF4-Arie/allegromoderato.ly'
Parsing...
Interpreting music...Backtrace:
0* ["Pitch::less_p" #<Pitch a > #<Pitch ees >]

ERROR: In procedure apply:
ERROR: Wrong type argument in position 1:
"Pitch::less_p"
warning: lilypond: command exited with value 512
(ignored)
warning: no lilypond output found for
/home/Default/MF4-Arie/allegromoderato
Running LaTeX...
Running dvips...
error: dvips: command exited with value 256
Traceback (most recent call last):
  File "/usr/lilypond-1.5.60.jcn1-1/bin/ly2dvi", line
943, in ?
    run_dvips (outbase, extra_init)
  File "/usr/lilypond-1.5.60.jcn1-1/bin/ly2dvi", line
709, in run_dvips
    quiet_system (cmd, 'dvips')
  File "/usr/lilypond-1.5.60.jcn1-1/bin/ly2dvi", line
442, in quiet_system
    return system (cmd)
  File "/usr/lilypond-1.5.60.jcn1-1/bin/ly2dvi", line
247, in system
    error (msg)
  File "/usr/lilypond-1.5.60.jcn1-1/bin/ly2dvi", line
144, in error
    raise _ ("Exiting ... ")
Exiting ...
MIDI output to `allegromoderato.midi'...
address@hidden ~/MF4-Arie$

If I take out the <> and just have one note,
everything works perfect. Any suggestions?

Thank you!

Deborah