Sequences problem

Hello everybody, I have a question related with sequences.............

When I init a sesion with my db, if a do the next sentence:
   SELECT   currval('pagos_id_pago_seq');


return this:  ERROR: the relation doesn't exist   (or somethimg like that, because the message is in spanish)

but if I do first,
   SELECT nextval('pagos_id_pago_seq');

and then   SELECT currval('pagos_id_pago_seq');   it success, returns the 
current sequence value,  it is possible to indicate that the sequence is 
already started and in the value 4567 but I need first to now the 
current value before the next, how can I do?
   Thanks in advanced