plpgsql function

Hi,
creation of following function works just fine but usage not:):
mtldb=# select mtldb_wykonane(0);
ERROR: unexpected SELECT query in exec_stmt_execsql()
Can You help me find an error?
tia

CREATE FUNCTION mtldb_wykonane (integer) RETURNS integer AS '
DECLARE
zlecenie alias for $1;
tls integer;
twz integer;
BEGIN
SELECT count(*) as ls FROM serwery;
tls:=new.ls;
SELECT count(*) as wz FROM wykonanie
WHERE zadanie_id=zlecenie AND kiedy IS NOT NULL;
twz:=new.wz;

if tls>twz
RETURN -1;
end if;
if tls=twz
RETURN 1;
end if;
END;
' LANGUAGE 'plpgsql' ;

Marcin Mazurek

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