lilypond errors on a guitar minor sixth chord

[Stan Mulder]

I would seem that lilypond doesn't like minor sixth chords. All my guitar fretboards seem to be fine, but I get errors on all chords with a minor sixth. Here's some of the code:

b-flat4 bf/f g4:dim/e e-flat:m6

Here's the corresponding error complaining about the "m6"

warning: No string for pitch #<Pitch ees' > (given frets (11 11 8))

b-flat4 bf/f g4:dim/e

e-flat:m6

[8][16][24]

If i remove the sixth and just make it an "e-flat:m", there's no error.

I thought a minor sixth was pretty standard. Or am I misinterpreting the error?

I have \include "predefined-guitar-fretboards.ly" at the top of the file...

I'm using \version "2.19.49"

Stan