SYSTEM as SYSDBA cannot grant privs on others' tables?

I'm trying to set up a complex set of schemas and want to do all the work logged on as SYSTEM. I can create tables in other schemas, but when I try to grant privileges on those tables (to PUBLIC, for instance) Oracle tells me I have insufficient privileges. For example:

   grant select on mfg.orders to public;    ORA-01031: insufficient privileges

I'm logged on as SYSTEM. It makes no difference if I use "as SYSDBA" also. As far as I can tell, SYSTEM has all necessary privileges.... what am I missing?

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Jim Garrison (jhg_at_acm.org) 
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