The button's name is «Scegli file» (Italian version, it means choose file) and it always fails.
I wonder whether I should put brackets or else into the buttons name, or an underscore. Maybe it fails for the space between words?
Without being able to see your workflow or macro it's hard to tell. Just to confirm though, does the button itself contain those angular quotation marks? « »
Or did you put those in your post because that is how Italian indicates a quotation? I know in Spanish, they use those types quotation marks...
If you mean while setting an attachment, and you're in the file selector dialog, then the button is the default button, so simply using Type a KeystrokeReturn should work.