detecting if fails in a macro?

[Louis-David Mitterrand]

Hi,

I have this macro to archive messages:

macro pager,index Sl "<tag-pattern>~h'Return-Path: 
<u...@example.com>'<enter><tag-prefix><save-message>=Archive<enter>" "archive 
messages"

But if no messages have been tagged then <tag-prefix> fails and the
currently hightlighted message gets archived.

What is the correct way to do it?

Thanks,