UART1 Module always enters to UART1_Handler even if there is no data in RX line

Hello 

I need to use UART1 Module in one application. I use Tiva TM4C123GXL Board. Thats why I activated UART1 Module. But the problem is that My code always enters to UART1_Handler and thats why my code does not enter main loop even if there are any data in RX pin of UART1 Module. The problem is same wirh UART3 Module too. But UART0 module works fine with same config

My UART initilization and Handler function in below

void UART1_Init(void)
{
  SYSCTL_RCGCUART_R |= 0x02;                            // Activate UART1
  SYSCTL_RCGCGPIO_R |= 0x02;                            // Activate port B
  UART1_CTL_R &= ~UART_CTL_UARTEN;                      // Disable UART
  UART1_IBRD_R = 260;                                   
  UART1_FBRD_R = 27;                                  

  UART1_LCRH_R = (UART_LCRH_WLEN_8 | UART_LCRH_FEN);    // 8 bit word length (no parity bits, one stop bit, FIFOs)

  UART1_IFLS_R &= ~0x3F;                                // Clear TX and RX interrupt FIFO level fields
                                                        // Configure interrupt for TX FIFO <= 1/8 full
                                                        // Configure interrupt for RX FIFO >= 1/8 full
  UART1_IFLS_R += (UART_IFLS_TX1_8|UART_IFLS_RX1_8);    // Enable TX and RX FIFO interrupts and RX time-out interrupt
  // UART1_IM_R |= (UART_IM_RXIM|UART_IM_TXIM|UART_IM_RTIM);
  UART1_IM_R  |= (UART_IM_RXIM | UART_IM_RTIM);         // UART Receive Interrupt Mask | UART Receive Time-Out Interrupt
  UART1_CTL_R |= UART_CTL_UARTEN;                       // Enable UART

  GPIO_PORTB_AFSEL_R |= 0x03;                           // Enable alt funct on PB1-0
  GPIO_PORTB_DEN_R   |= 0x03;                           // Enable digital I/O on PB1-0

  GPIO_PORTB_PCTL_R  = (GPIO_PORTB_PCTL_R&0xFFFFFF00)+0x00000011;  // Configure PB1-0 as UART
  GPIO_PORTB_AMSEL_R = 0;                                          // Disable analog functionality on PB

  NVIC_PRI1_R = (NVIC_PRI1_R&0xFFFF00FF)|0x00004000;               // UART0=priority 2, Bits 13-15
  NVIC_EN0_R = NVIC_EN0_INT6;                                      // Enable interrupt 6 in NVIC
}

void UART1_Handler(void)
{
    if(UART1_RIS_R&UART_RIS_RXRIS)
      {       // hardware RX FIFO >= 2 items
        UART1_ICR_R = UART_ICR_RXIC;        // acknowledge RX FIFO , RX Interrupt Clear
      }
}

Regards

Serkan