Editing Appearances with Macros

Hello guys,

since I am trying out some macro stuff I ran into the following problem:

I would like to edit the Image assigned to an appearance using a macro but i couldn't figure out the command.

I tried 100 different ways. something like:

Edit Appearance 19 property "Image" "3.1"

(using OnPC with command wing)

Perfect, that is exactly what i missed??

Thank you!