Help with Chordname

[Steve Noland]

Hello,

I am trying to typeset a score for jazz orchestra.  I am having problems with 
some of the jazz chordnames engraving correctly.  Specifically, a Dm7(b5) chord 
(D minor 7, flat 5) engraves as a Dº, or D diminished.  What can be the problem?

Here is a code snippet:

theChords = \chordmode { 
    s1*3 
    c1:m s1*4 d1:m7.5- g1:7sus4 c2 b2:m11 

And the resultant score:

ChordSnip.pdf
Description: ChordSnip.pdf