NFS sharing /usr/ports and /usr/src

[Tom Munro Glass]

I want to NFS share /usr/ports and /usr/src from a master machine for use by 
other machines. If I specify -network and -mask options for each share, I get 
the error:

	mountd[101]: can't change attributes for /usr/src
	mountd[101]: bad exports list line /usr/src

but if I don't have any options, the share works OK?

What am I doing wrong?

Tom Munro Glass