单片机STM32F103 将UART4设置为使能中断则程序无法运行

单片机STM32F103 将串口UART4设置为使能中断则程序无法运行，注释掉USART_ITConfig( UART4, USART_IT_RXNE, ENABLE)程序就可以运行了，为什么会这样呢？

UART4配置代码：

void USART4_Init( unsigned int baud )
{
                GPIO_InitTypeDef gpioInitStruct;
                USART_InitTypeDef usartInitStruct;
                NVIC_InitTypeDef nvicInitStruct;

                RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOC, ENABLE );
                RCC_APB1PeriphClockCmd( RCC_APB1Periph_UART4, ENABLE );

                gpioInitStruct.GPIO_Pin = GPIO_Pin_10;
                gpioInitStruct.GPIO_Mode = GPIO_Mode_AF_PP;
                gpioInitStruct.GPIO_Speed = GPIO_Speed_50MHz;
                GPIO_Init( GPIOC, &gpioInitStruct );

                gpioInitStruct.GPIO_Pin = GPIO_Pin_11;
                gpioInitStruct.GPIO_Mode = GPIO_Mode_IN_FLOATING;
                gpioInitStruct.GPIO_Speed = GPIO_Speed_50MHz;
                GPIO_Init(GPIOC, &gpioInitStruct);

                usartInitStruct.USART_BaudRate = baud;               
                usartInitStruct.USART_WordLength = USART_WordLength_8b;               
                usartInitStruct.USART_StopBits = USART_StopBits_1;                               
                usartInitStruct.USART_Parity = USART_Parity_No;                                       
                usartInitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;               
                usartInitStruct.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;               
                USART_Init( UART4, &usartInitStruct );

                USART_Cmd( UART4, ENABLE );                                                                                                       

//                USART_ITConfig( UART4, USART_IT_RXNE, ENABLE);                                                // 带着这行代码就无法运行，注释掉后可以运行！！！！！！
                USART_ClearFlag( UART4, USART_FLAG_TC );                                                                        

                nvicInitStruct.NVIC_IRQChannel = UART4_IRQn;
                nvicInitStruct.NVIC_IRQChannelPreemptionPriority = 3;                       
                nvicInitStruct.NVIC_IRQChannelSubPriority = 3;                                               
                nvicInitStruct.NVIC_IRQChannelCmd = ENABLE;
                NVIC_Init(&nvicInitStruct);

}