HELP - instatiating a componet

Hi everybody,

I'm new to VHDL and I'm doing a project for uni. I'm having problems 
instatiating a component in a project: I'm trying to build a slow 
counter by using a clock divider and a 8-bit counter. I'm sure both the 
counter and the divider work, taken separately. Now, I want to reuse the 
code for the counter, instatiate the freq div to obtain a "slow counter" 
driven by the clock. However, the code below yields "output pins stuck 
to GND or VCC". Can anyone see why ?

Thanks

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

entity slow_cnt2 is
    port (
      clock: in std_logic;
      rst: in std_logic;
      Q: out std_logic_vector ( modulus-1 downto 0)
      );
end slow_cnt2;

architecture bhv of slow_cnt2 is

    signal tcount: std_logic_vector (modulus-1 downto 0);  -- inner 
counter
    signal slowclk : std_logic;

    component clk_div is
        port (
          clk: in  std_logic;
          clkout : out std_logic);
    end component;

begin  -- bhv

    divider : clk_div port map (
      clk    => clock,
      clkout => slowclk);

    count: process (slowclk, rst)
    begin  -- process count
        if rst = '0' then                   -- asynchronous reset 
(active low)
            tcount  <= (others => '0');
        elsif slowclk'event and slowclk = '1' then
            tcount <= tcount + '1';
        end if;
    end process count;
    Q <= tcount;
end bhv;