EK-TM4C123GXL: Why I'm not able to put the breakpoints??

Part Number: EK-TM4C123GXL

I have attached my code below. In which I was trying to put breakpoints but not able to do so. What should be the reason??

#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_ints.h"
#include "inc/hw_memmap.h"
#include "inc/hw_nvic.h"
#include "inc/hw_types.h"
#include "driverlib/debug.h"
#include "driverlib/fpu.h"
#include "driverlib/gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/pin_map.h"
#include "driverlib/rom.h"
#include "driverlib/rom_map.h"
#include "driverlib/sysctl.h"
#include "driverlib/systick.h"
#include "driverlib/uart.h"
#include "utils/uartstdio.h"

volatile uint32_t g_ui32Index;

volatile uint32_t g_ui32GPIOa;

void Delay(uint32_t ui32Seconds)
{
    //
    // Loop while there are more seconds to wait.
    //
    while(ui32Seconds--)
    {
        //
        // Wait until the SysTick value is less than 1000.
        //
        while(MAP_SysTickValueGet() > 1000)
        {
        }

        //
        // Wait until the SysTick value is greater than 1000.
        //
        while(MAP_SysTickValueGet() < 1000)
        {
        }
    }
}

void IntGPIOa(void)
{
    //
    // Set PE1 high to indicate entry to this interrupt handler.
    //
    MAP_GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_1, GPIO_PIN_1);


    // Wait two seconds.
    //
    Delay(2);

    //
    // Save and increment the interrupt sequence number.
    //
    g_ui32GPIOa = g_ui32Index++;

    //
    // Set PE1 low to indicate exit from this interrupt handler.
    //
    MAP_GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_1, 0);
}

void UART0_init(uint32_t SysClock)
{
	  SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);

    GPIOPinConfigure(GPIO_PA0_U0RX);
    GPIOPinConfigure(GPIO_PA1_U0TX);

    GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);

    UARTConfigSetExpClk(UART0_BASE,SysClock, 115200,
                        (UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |
                         UART_CONFIG_PAR_NONE));
	  UARTStdioConfig(0, 115200, SysClock);	
}

void UART_SendData(unsigned char c)
{
    UARTCharPut(UART0_BASE, c);
}

char UART_GetData()
{
	char d;
	d = UARTCharGet(UART0_BASE);
	return (d);
}

int main(void)
{
    uint32_t ui32SysClock;
    char Tx;

    SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
                   SYSCTL_XTAL_16MHZ);
    ui32SysClock = SysCtlClockGet();
	
	  UART0_init(ui32SysClock);
	
	  UARTprintf("Enter the data\n");
	
		while(1)
		{
			Tx = UART_GetData();
			UART_SendData(Tx);
		}
    MAP_SysTickPeriodSet(MAP_SysCtlClockGet());
    MAP_SysTickEnable();

		MAP_IntMasterEnable();
    MAP_IntEnable(INT_GPIOA_TM4C123);
		MAP_IntPrioritySet(INT_GPIOA_TM4C123, 0x00);
		
}