can't modify subject from macro?

[Louis-David Mitterrand <vindex+lists-mutt-users@xxxxxxxxxxx>]

Hi,

I have this spam reporting macro:

        macro index,pager Sy "<enter-command>set mime_fwd ; my_hdr To: 
abuse@xxxxxxxxx; my_hdr Subject: SPAM report;<enter><forward-message>"

which works apart from the subject modification 'my_hdr'.

Is there another way of doing it?

Thanks,