Adding note head to incompatible stem problem

[Deborah Lowrey]

Dear Lilypond,

I have a section of 4 measures I'm having a problem
with. The Clarinet's staff produces the error:

address@hidden ~/MF7-Duett$ ly2dvi -P lilyproblem.ly
Running LilyPond...
 -I /home/Default/MF7-Duett -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 l
anguage -H latexheaders -H latexoptions -H linewidth
-H latexpackages -H unit -H
 orientation /home/Default/MF7-Duett/lilyproblem
GNU LilyPond 1.5.66.jcn1
Now processing:
`/home/Default/MF7-Duett/lilyproblem.ly'
Parsing...
Interpreting music...
/home/Default/MF7-Duett/lilyproblem.ly:10:8: warning:
Adding note head to incomp
atible stem (type = 8):
        r4 r8 c
               4. ~

/home/Default/MF7-Duett/lilyproblem.ly:12:8: warning:
Adding note head to incomp
atible stem (type = 8):
        r4 c8 c
               4. ~
[3]
Preprocessing elements...
Calculating column positions... programming error: No
StaffSpacing wishes found
(Continuing; cross thumbs)
programming error: No StaffSpacing wishes found
(Continuing; cross thumbs)

paper output to `lilyproblem.tex'...

Interpreting music...
MIDI output to `lilyproblem.midi'...
Track ...
Analyzing lilyproblem.tex...
Running LaTeX...
Running dvips...
DVI output to `lilyproblem.dvi'...
MIDI output to `lilyproblem.midi'...
PS output to `lilyproblem.ps'...
address@hidden ~/MF7-Duett$


But the Fagotti's 4 measures comes out correct. The
sample four measures are as follows:

clarinettiI = \notes \relative c'' {

        r4 r8 [c8.( f16 a f] 
        )e8 r r r4 r8
        r4 c8 [c8.( f16 a f]
        )e8 r r r4 r8 }

clarinettiII = \notes \relative c'' {

        r4 r8 c4. ~ 
        c8 r r r4 r8
        r4 c8 c4. ~
        c8 r r r4 r8 }

fagottiI = \notes \relative c' {

        r4 r8 \clef tenor bes4( ees16 )g
        f8 r r r4 r8
        r4 bes,8 bes4( ees16 )g
        f8 r r r4 r8 }

fagottiII = \notes \relative c' {

        r4 r8 \clef tenor bes4( )ees8
        d8 r r r4 r8
        r4 bes8 bes4( )ees8
        d8 r r r4 r8 }

I'm using Voice \partcombine to produce two staffs.
How can I get the quarter stem (down) to show with the
8. stem (up). I've tried using \stemDown and \stemUp
but they do not change anything.  Any suggestions?

Thanks!

Deborah