I know that it's been a few days since you've asked that question, but I think that you must've mistyped something. Here's my entire line of code that is in my file now, and I've got it working.
<td class="windowbg2" align="center" valign="middle" width="22%"><font size="1">$latestPostTime<br /><a href="$scripturl?board=$row_board[ID_BOARD];action=display;threadid=$topicID;start=new"><img border="0" src="$imagesdir/lastpost.gif" alt="$subject"></a> $txt[525] $latestPostName</a></font></td>
Highlight + copy that into a .txt file, and replace all of what you have with it, and it should work for ya. It seems to me, that somehow, you removed the 'Today at: Date' somehow, which is the line of code
$latestPostTime
I noticed it, and I suck at PHP.

Check your code to see if you're missing that, though you can make it easier and just highlight + copy what I've put above.
Here's the link to my setup.
http://www.ufba.org/forum/index.php