I have installed Oracle 9 and it has generated the initial db without any problems. The db is running but when I attempt to perform the following

sqlplus /nolog

connect / as sysdba
connect system/@DB AS systdba

I get the ORA-01031: insufficient privileges message.

I understand that this may be a groups issue but the Oracle9 user is assigned to the dba group although the Primary group is orainventory.

I have just investigated this further and can do a

conn sys/ as sysdba

I am missing something here. Apologies for the dumb questions but I haven't touched DBA work for 2-3 years so a little rusty !!