[WIN7] Defraggler fails to defrag external hard drive(s)

Here's the skinny, Got an external hard drive - a Seagate GoFlex, specifically. It's the kind that basically turns on with the PC, and Windows 7 is configured to do weekly backups to it (system image & file). So naturally, Windows rather whores out the space on that drive. I am running the latest available version of DeFraggler, to help with the fragmentation on my boot drive just fine. The problem is, that no matter how often I attempt to do so, Defraggler fails to even analyze, much less defrag, the external. The last time I was somehow able to trick it into completing an analysis, it's reporting about 53% fragmentation. :o Worse, Windows' own defrag utility insists there's no problem with that drive, and won't defrag it either. And in practice, attempting to set a boot-time defrag never works, either. So what do I do to resolve this so I can defrag the external(s) like I would my internal? Suffice to say, Defraggler seems to just not like attempting to defrag ANY external drives... but the one that is in most dire need of it, is the one that is configured for handling my scheduled backups. :( -- Because, f*ck Sony