I have no experience with the Novell platform, but from general experience:
Experiment via 'dsmc query archive' before attempting 'dsmc retrieve', to 
verify the existence of your quarry.
Examine your retention values: the files of interest might have aged out.
Make sure you are either the owner of the files or a superuser, for the access 
attempt to work.
You could also try putting braces around the filespace-specific portion of the 
path name, which at least on other platforms is a way of keeping the client 
from being confused as to how much of the path is the filespace name.  (You can 
do 'dsmc query filespace' to verify what's out there.)

    Richard Sims