What's wrong with this flashing code?

[MyvB8MyIPS]

We're trying to make a flashing PM indicator. The reason why we can't use one of the others already out is because our style already uses a gif image in the background for the PM section. So what we're trying to do is to make it flash when a new PM arrives. The second image is called pmalert.gif. Ypu can ignore the mem_left.gif and mem_right.gif images. Here is the code that we've made so far:

  <!-- nav buttons bar -->
<div align="center">
<table width="30%" cellpadding="0" cellspacing="0" align="center"><tr>
<td><img src="$stylevar[imgdir_misc]/mem_left.gif" alt="" border="0" /></td>
<td width="50%" class="membersbar">
</td>
<td width="40%" align="center" class="membersbar">
<if condition="$show['pmstats']"> <phrase 1="$vbphrase[unread_x_nav_compiled]" 2="$vbphrase[total_x_nav_compiled]" 3="$session[sessionurl]">$vbphrase[private_messages_nav]</phrase></if>
<else />
<if condition="$bbuserinfo['pmunread']"> 
				 <img src="$stylevar[imgdir_misc]/pmalert.gif" alt="" border="0" />
	</if> 
</td>
<td><img src="$stylevar[imgdir_misc]/mem_right.gif" alt="" border="0" /></td>
</tr></table>
</div>
<!-- / nav buttons bar -->

The problem is that the "else" tag isn't working, and when a PM arrives it tries to display TWO images there at the same time Is there a way that we can fix this so that it switches to the other image wien a PM arrives?

Thanks.