mysql accusing error when trying to insert a timestamp

I'm trying to pass a timestamp per parameter to a function, but I end up getting a

ERROR:  invalid input syntax for type time: "10"

The section where I pass is:

select agendar('2010-01-01 10:00:01')

The snippet you receive is:

CREATE OR REPLACE FUNCTION agendar(dia timestamp) returns bool as $$
declare

-- aqui eu declaro as variaveis....
begin
-- aqui o meu codigo
end
$$ language plpgsql