Doesn't defrag much

Ran Defraggler on a Windows 7 computer ... started with 43% fragmentation. After a coupld of hours it finished with still 41% fragmentation. Why is it not defragging? I'm using the default settings. Any suggestions? Thanks.

Try this

http://forum.piriform.com/index.php?showtopic=34115&view=findpost&p=203539