Recuva fails to recover data from a password protected user account

I tried to recover data recently from a harddisk that I connected externally to a USB drive enclosure to read it on my pc.

First, I tried Recuva to see if it would recover any data at all from that user folder, & it failed to see anything.

Next, I tried Handy Recovery, & when I navigated to that directory, all the data was visible & recoverable.

I was just wondering if there is something that Recuva is missing or isn't checking that Handy Recovery is? Perhaps it is reading at a lower level than Recuva is? Why is Handy Recovery able to recover all the data on the password protected user account & Recuva cannot?

It is a standard password protected XP Pro account, E:/Documents and Settings/Emanuel

Just wondering if there is a way of scanning to produce more results that Recuva is missing? I am puzzled by what Handy Recovery is doing different that Recuva isn't...

Also, some drive have a long scan time, especially large ones. There is a pause on Defraggler, so why not Recuva as well?