Vista - Robocopy copies same files again and again.

Hi,

I'm new to using robocopy but I have used it for awhile with a couple of external drives to keep them in sync but using a simple command like:

robocopy g: f: /E /R:2

this copies everything from the g: drive to the f: drive including empty directories and tries 2 times for failures.

On my desktop which is a XP Pro machine as well, I've installed the Windows Resource Kit Tool which includes robocopy and am trying to do a similar thing to copy my "My Documents" directory on my c: drive to my k: drive which is an external drive on my mionet network. The copy does work fine but each time I run the robocopy command, a large number of the files get copied even though they haven't changed. I'm sure that I'm just missing something but I've tried adding things to the command line to not copy older files. Here's something that I have tried:

robocopy "C:\Documents and Settings\Administrator\My Documents" "K:\ImageThat\My Documents" /E /R:2 /XO /A-:A

each time that I execute this command, I get about 800 files that get copied and I don't understand why. Anyone see anything that I'm missing, or perhaps the way that I am understanding how robocopy works is the problem.

thanks in advance!
Bill