Can internal root server also forward?

[joeunc]

Have an internal root server with zone db.root.
Forwarding is not turned on as global option. Tried to add two forward
zones with forward only into the root server and it would never
forward. NXDOMAIN on localhost digs for that forward zone. If the zone
is delegated in the the db.root file with NS  records it works
obviusly, The internal root server is running BIND 9.2.2.

Are there limitations on a root server having forward only zones?

thanks
Joe