no aoutput from plpgsql-function

Hello everybody

I am trying to write a plpgsql-function. The function-body is as follows:

declare
  autor alias $1;
begin
  return p_id from publikation (here are two joins) where m_name = ''autor'';
end;

When I run this function, I get no output. psql shows me:

test=# select suche('Egon');
 suche
-------

(1 row)

Can someone give me a hint why the function does'nt display the value of the id? It is existing in the table and it is
nota NULL-value.  

Thanks
Conni