Error 10500 Help me !!!

so this is one of my first VHDL codes...

(havent finished the cnt select part on the bottom^^)

I get some "10500 vhdl Syntax error"s between 'begin' and 'with cnt select'... But why?? :(:confused:

I can't find anything missing ._.

library ieee;

use ieee.std_logic_1164all;

entity helloworld is

port(key0: IN STD_LOGIC;

Hex0: OUT STD_LOGIC_VECTOR(6 downto 0)

);

end helloworld;

architecture behaviour of helloworld is

signal a: STD_LOGIC;

signal cnt: STD_LOGIC := '0';

begin

a <= not key0;

if a = '1' then

cnt <= cnt + 1;

end if;

if cnt = '16' then

cnt <= '0';

end if;

with cnt select

.

.

.

end behaviour;