I'm just trying to change the From user before I do a 301 Redirect within a Failure Route.  Here's the code snippet:

$fu = "+15555555555";

append_to_reply("Contact: sip:+1$var(redirect_did)@$si:$sp\r\n");
t_reply("302", "Redirect");

The From user is not changed and msg_apply_changes() isn't allowed.  What am I doing wrong?

Thanks