Ligatures

Hej All
I’ve got a problem with Ligatures. I work on a consisting fonts. I tried to create a new ligature:

sub g g by g_g; (in features > dlig)

But it doesn’t work an when I try to export, the following error-notification is appears:

Duplicate target glyph for single substitution in ‘sups’ feature: zero
Es wurde keine Datei erzeugt.

I haven’t find a solution till jet and I would be happy to solve the problem.

The problem us in the “subs” feature. Probably because you have .subs and .sinf figures.