Amazing problem with a variable

Here is the whole code:

library ieee;

use ieee.std_logic_1164.all;

use ieee.std_logic_unsigned.all;

use ieee.numeric_std.all;

entity compteur_moyen_deph is

port(

-- Input

clk : in std_logic;

arazb : in std_logic;

En_enteteRX : in std_logic;

En_enteteRX_nbdeph : in std_logic_vector(7 downto 0);

flag_moyennagetermine : in std_logic;

-- Output

cpt_deph : out std_logic_vector(5 downto 0):= (others => '0');

nb_deph : out std_logic_vector(7 downto 0):= (others => '0');

flag_nbdeph : out std_logic :='0';

en_finmesurereflecto : out std_logic :='0';

en_actmoyennage : out std_logic :='0'

);

END compteur_moyen_deph;

ARCHITECTURE ar_compteur_moyen_deph OF compteur_moyen_deph IS

BEGIN

PROCESS(clk,arazb) IS

variable v_tempo_En_enteteRX : std_logic :='0';

variable v_tempo_flag_moyennagetermine : std_logic :='0';

variable v_attente : std_logic :='0';

variable v_reset_flag_nbdeph : std_logic :='0';

variable v_flag_nbdeph : std_logic :='0';

variable v_nb_deph : std_logic_vector (7 downto 0):= (others => '0');

variable v_cptdeph : std_logic_vector (5 downto 0):= (others => '0');

variable v_en_finmesurereflecto : std_logic :='0';

variable v_en_actmoyennage : std_logic :='0';

BEGIN

--reset

IF arazb ='0' THEN

--variables

v_tempo_En_enteteRX :='0';

v_tempo_flag_moyennagetermine :='0';

v_attente :='0'; -- modif: v_attente := '1'

v_reset_flag_nbdeph :='0';

v_flag_nbdeph :='0';

v_nb_deph := (others => '0');

v_cptdeph := (others => '0') ;

v_en_finmesurereflecto :='0';

v_en_actmoyennage :='0';

--output

cpt_deph <= (others => '0') ;

nb_deph <= (others => '0');

flag_nbdeph <='0';

en_finmesurereflecto <='0';

en_actmoyennage <='0';

ELSIF RISING_EDGE(clk) then

IF (En_enteteRX ='1' AND v_tempo_En_enteteRX ='0')AND v_en_finmesurereflecto ='0' THEN

v_attente_nbdeph :='1';

ELSIF v_attente_nbdeph = '1' THEN

v_cptdeph := "000001";

ELSIF v_cptdeph = "000001" AND v_cptdeph <= En_enteteRX_nbdeph THEN

v_nb_deph <= X"01";

v_attente_nbdeph := '0';

v_flag_nbdeph :='1';

ELSE

v_flag_nbdeph := '0';

v_en_finmesurereflecto :='0';

v_attente_nbdeph := '0';

v_en_actmoyennage:= '0';

v_nb_deph <= X"FF"; --HERE MY PROBLEM, this value doesnt' change to FF.....only X"03"

END IF;

v_tempo_flag_moyennagetermine := flag_moyennagetermine;

v_tempo_En_enteteRX := En_enteteRX ;

ELSIF FALLING_EDGE(clk) then

cpt_deph <= v_cptdeph;

nb_deph <= v_nb_deph; -- So this output is not updated to the right value

flag_nbdeph <= v_flag_nbdeph ;

en_finmesurereflecto <= v_en_finmesurereflecto;

en_actmoyennage <= v_en_actmoyennage;

END IF;

END PROCESS

END ar_compteur_moyen_deph;

And here is the testbench which as been done with Modelsim-altera 6.6d: