array function problem

I have a array function
CREATE OR REPLACE FUNCTION "temp".rowfromarray(text[])
RETURNS SETOF text AS
$BODY$DECLARE
_return text;
BEGIN
for i in 1..array_upper($1,1) loop
_return := $1[i];
return next _return;
end loop;
return;
END;$BODY$
LANGUAGE 'plpgsql' VOLATILE
COST 100
ROWS 1000;
ALTER FUNCTION "temp".rowfromarray(text[]) OWNER TO postgres;

I call it by command
select temp.rowfromarray(string_to_array('1,2,3,4,5', ','));
but it have error

ERROR: set-valued function called in context that cannot accept a set
CONTEXT: PL/pgSQL function "rowfromarray" line 6 at RETURN NEXT

********** Error **********

ERROR: set-valued function called in context that cannot accept a set
SQL state: 0A000
Context: PL/pgSQL function "rowfromarray" line 6 at RETURN NEXT

When i debug it by pass {1,2,3,4,5} to first parameter, it run well.

Please help me.
Thanks you very much. Sorry for my English.