stm32f407定时器9不运行。。。为什么？

tiM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
        NVIC_InitTypeDef NVIC_InitStructure;
        
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM9,ENABLE);  ///
        
  TIM_TimeBaseInitStructure.TIM_Period = arr;         //
        TIM_TimeBaseInitStructure.TIM_Prescaler=psc;  //
        TIM_TimeBaseInitStructure.TIM_CounterMode=TIM_CounterMode_Up; //
        TIM_TimeBaseInitStructure.TIM_ClockDivision=TIM_CKD_DIV1;
        
        TIM_TimeBaseInit(TIM9,&TIM_TimeBaseInitStructure);//
        TIM_ITConfig(TIM9,TIM_IT_Update,ENABLE); //
        TIM_Cmd(TIM9,ENABLE); //ʹÄܶ¨Ê±4
        NVIC_InitStructure.NVIC_IRQChannel=TIM1_BRK_TIM9_IRQn; //
        NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);//
        NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=1; //
        NVIC_InitStructure.NVIC_IRQChannelSubPriority=2; //
        NVIC_InitStructure.NVIC_IRQChannelCmd=ENABLE;
        NVIC_Init(&NVIC_InitStructure);