Sorting in therads

Mhonarc is sorting my thead index after the date of the FIRST message in a  
thread, is there anyway to get it to sort after the LAST message in the thread ?
I want to keep the most resent thread in top - not on page 2 ,3 or 4.

I'am using  
<MULTIPG>
<IDXSIZE>
40
</IDXSIZE>
<MAXSIZE>
0
</MAXSIZE>
<TSORT>
<TREVERSE>

Mvh
Birger