Without anymore info, all I can say is that more then likely, those fragmented files are locked system files that cannot be moved while the OS is active. You would need to perform a "Boot Time Defrag" or "Offline Defrag" which would defrag system files before the OS is loaded, the next time you reboot.
However, someone please chime in on this part as I am not 100% sure this is true, but there are some files that should not be relocated from their current location, but any recent defrag program made for Win7 should know what not to move.
Btw, I used to also use Diskeeper as well, but then changed over to PerfectDisk. Much faster defrag and now so much more better then before with its Stealth defrag (defrags any disk you setup while idle).