using sequences

I have read the manual about sequences and I thought I understood both
their purpose and how to use them.  When I perform inserts, the sequence
is updated appropriately.  However, I can't seem to directly access the
sequence myself.  I always seem to get this message:

be_db=# select currval('news_news_id_seq');
ERROR:  news_news_id_seq.currval is not yet defined in this session

Can someone explain what is going on?


Thank you,

Erik