CAN Bus Porblem auf STM32

Hallo ich habe folgendes Problem:

Mein Bus läuft gut auf 125 KBit. Wenn ich allerdings den Prescaler von 
16 auf 8 runter stelle läuft nichts mehr. Die Clock bzw. Timer müssten 
alle passen, sonst würde der CAN ja auch in 125k nicht laufen !?
Die LED in dem Code ist nur zur Kontrolle ob der Timer richtig läuft. 
Ossi ist vorhanden.
Hier der Code:

#define HSE_VALUE    ((uint32_t)8000000)


/* Includes */
#include <stddef.h>
#include "stm32f2xx.h"

#define CAN1_TX GPIO_Pin_12
#define CAN1_RX GPIO_Pin_11
#define CAN_PORT GPIOA
#define CAN_GPIO_CLK RCC_AHB1Periph_GPIOA
#define CAN_TX_SOURCE GPIO_PinSource12
#define CAN_RX_SOURCE GPIO_PinSource11



//====================================================================== 
=====

volatile uint8_t a=0;

void SetupPeripherie (void) {
  GPIO_InitTypeDef  GPIO_InitStructure;

  // GPIOD Takt freigeben
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);

  // LED-GPIO als Ausgang konfigurieren
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
  GPIO_Init(GPIOB, &GPIO_InitStructure);


}
void Delay(__IO uint32_t nCount) {
  while(nCount--) {
  }
}

void Timer_Initt(void)
{
  TIM_TimeBaseInitTypeDef TIM_TimeBase_InitStructure;
  NVIC_InitTypeDef NVIC_InitStructure;

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
//Einstellung Timer auf 100 ms
    TIM_TimeBase_InitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBase_InitStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBase_InitStructure.TIM_Period = 6000-1;
    TIM_TimeBase_InitStructure.TIM_Prescaler = 1000-1;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBase_InitStructure);

    TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);

    NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0F;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F;
    NVIC_Init(&NVIC_InitStructure);

    TIM_Cmd(TIM2, ENABLE);
}



void TIM2_IRQHandler(void){
/*
  a++;
  if (a==100)
  {
    GPIO_ToggleBits(GPIOB,GPIO_Pin_2);
    a=0;
  }
  */
  GPIO_ToggleBits(GPIOB,GPIO_Pin_2);

  CanTxMsg canMessage;

      canMessage.StdId = 0x14;
      canMessage.ExtId = 0;
      canMessage.RTR = CAN_RTR_DATA;
      canMessage.IDE = CAN_ID_STD;
      canMessage.DLC = 8;

      canMessage.Data[0] = 0;
      canMessage.Data[1] = 1;
      canMessage.Data[2] = 2;
      canMessage.Data[3] = 1;
      canMessage.Data[4] = 0;
      canMessage.Data[5] = 1;
      canMessage.Data[6] = 4;
      canMessage.Data[7] = a;

      CAN_Transmit(CAN1, &canMessage);
a++;

    TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
}


void CAN_Initt(void)
{


  GPIO_InitTypeDef GPIO_InitStructure;


  RCC_AHB1PeriphClockCmd(CAN_GPIO_CLK, ENABLE);

    // Connect CAN pins to AF9
  GPIO_PinAFConfig(CAN_PORT, CAN_RX_SOURCE, GPIO_AF_CAN1);
  GPIO_PinAFConfig(CAN_PORT, CAN_TX_SOURCE, GPIO_AF_CAN1);

    // Configure CAN RX and TX pins
  GPIO_InitStructure.GPIO_Pin = CAN1_TX | CAN1_RX;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_Init(CAN_PORT, &GPIO_InitStructure);

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1, ENABLE);

  CAN_DeInit(CAN1);
  CAN_InitTypeDef CAN_InitStructure;

  CAN_InitStructure.CAN_Prescaler = 16;
  CAN_InitStructure.CAN_SJW = CAN_SJW_1tq;
  CAN_InitStructure.CAN_BS1 = CAN_BS1_6tq;
  CAN_InitStructure.CAN_BS2 = CAN_BS2_8tq;
  //CAN_InitStructure.CAN_SJW = CAN_SJW_1tq;
  //  CAN_InitStructure.CAN_BS1 = CAN_BS1_9tq;
  //  CAN_InitStructure.CAN_BS2 = CAN_BS2_5tq;
  CAN_InitStructure.CAN_Mode = CAN_Mode_Normal;
  CAN_InitStructure.CAN_TTCM = DISABLE;
  CAN_InitStructure.CAN_ABOM = DISABLE;
  CAN_InitStructure.CAN_AWUM = ENABLE;
  CAN_InitStructure.CAN_NART = DISABLE;
  CAN_InitStructure.CAN_RFLM = DISABLE;
  CAN_InitStructure.CAN_TXFP = DISABLE;
  CAN_Init(CAN1, &CAN_InitStructure);
}

int main(void)
{
  SystemCoreClock = HSE_VALUE;
  SetupPeripherie();
  Timer_Initt();
  CAN_Initt();

  while (1)
  {

  }
}