NFS Question on mounting

[CH]

I have Dapper on the server, Gutsy on one of the notebooks, and NFS capability 
installed on both, as far as I know.  When I attempt to mount a designated 
share, I get errors.  Frankly, the syntax has changed since I did this two or 
three years ago --according to what I can remember, that is.

root at laptop:/home/yogich# mount.nfs4 192.168.0.20:/Downloads /media/cdrom0
mount.nfs4: mount to NFS server '192.168.0.20' failed: System Error: 
Connection refused

root at laptop:/home/yogich# mount.nfs4 
192.168.0.20:/home/yogi/Downloads /media/cdrom0
mount.nfs4: mount to NFS server '192.168.0.20' failed: System Error: 
Connection refused

Pointers appreciated. :)