Navbar Hook?

[Kirk Y]

I'm trying to setup a rotating header on my forum that changes based on what day it is. I've got the coding all worked out and everything works fine except that I can't get the damn thing to work in the navbar. If I test it out using the forumhome_start hook it shows up fine -- but when I switch to global_start, it won't show up. Am I correct in thinking that global_start is the only hook that'll have an effect on the navbar? Thanks in advance if anyone has any ideas.

This is the plugin code I'm using:
$today2 = vbdate('l', TIMENOW, false, false);

if($today2==Monday){
$headimg = "<img src='images/rotators/header4.gif'>";
}

elseif($today2==Tuesday){
$headimg = "<img src='images/rotators/header3.gif'>";
}

elseif($today2==Wednesday){
$headimg = "<img src='images/rotators/header5.gif'>";
}

elseif($today2==Thursday){
$headimg = "<img src='images/rotators/header2.gif'>";
}

elseif($today2==Friday){
$headimg = "<img src='images/rotators/header1.gif'>";
}

elseif($today2==Saturday){
$headimg = "<img src='images/rotators/header3.gif'>";
}

elseif($today2==Sunday){
$headimg = "<img src='images/rotators/header5.gif'>";
}