Can't save movie captures to server...only to client

l have iMovie 11 (9.0) on a 10.6.8 client. I can't save movie clips to the server, but can save to the client. When I try to "File->Import from camera" (local iSight), then "capture", on the dialog that pops up I see "Save To:" with three shares:

1) "Mac HD" (local main partition),

2) "Data Store" (local data partition), and

3) "SERVER-USERDATA" (the main area on the server for network user data).

Share#1,2 show lots of gigs free, and I can save to these areas. (But I think I'll have a problem with network users if they log onto another machine, the clip won't be available.)

Share#3 shows 0gig free. But there is plenty of space on the server. If I try to save here, i get a dialog that says "... you may not have permissions to write to "/Network/Servers/rbserver.lan/SERVER-USERDATA/iMovieEvents.localized."

Where does it pull these sharepoints from? (SERVER-USERDATA is NOT a share of it's own, there are shares "under" it, like /server-userdata/students/...)

2 Questions:

1) any idea why it's not recognizing any free space on server share?

2) If I want to change the sharepoint that shows up for iMovie clip saving, where can I specify that? (on the client)