Fingering (two fingers/possibilities)

[Alberto Simões]

Hi, Folks

I have a chord, where the note at the top can use one of two fingers.
In the original music, it has a 2^1 notation (^ is a slur).

I tried something similar to

<g e^\markup { \finger "2 - 1" }>

(although this can be understood a a finger change)
But lilypond recuses to process it:

diabeli.op163.s2-1.ly:109:20: warning: can't add text scripts to 
individual note heads
                <g e
                    ^\markup { \finger "2 - 1" }>2( <g d>4 <g cis>)


Hints? Fixes?
Thanks ;)
--
Alberto Simões - Departamento de Informática - Universidade do Minho
                 Campus de Gualtar - 4710-057 Braga - Portugal