EK-TM4C123GXL LaunchPad M1PWM6 and M1PWM7 problem

Hi, I'm using CCSv6 and wrote some codes based on the Launchpad Workshop Lab 15.

#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "driverlib/sysctl.h"
#include "driverlib/gpio.h"
#include "driverlib/debug.h"
#include "driverlib/pwm.h"
#include "driverlib/pin_map.h"
#include "inc/hw_gpio.h"
#include "driverlib/rom.h"

#define PWM_FREQUENCY 200

int main(void) {

	volatile uint32_t ui32Load;
	volatile uint32_t ui32PWMClock;
	volatile int32_t i32DutyCycle = 500;

	// Run at 40 MHz
	ROM_SysCtlClockSet(SYSCTL_SYSDIV_5|SYSCTL_USE_PLL|SYSCTL_OSC_MAIN|SYSCTL_XTAL_16MHZ);

	// Set PWM clock at 40e6/64 = 625 kHz
	ROM_SysCtlPWMClockSet(SYSCTL_PWMDIV_64);

	// Enable M1PWMx
	ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM1);

	// Enable port F for PF4 (SW1), PF0 (SW2), PF2 (M1PWM6), PF3 (M1PWM7)
	ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);

	// Set PF2 and PF3 as PWM output pins
	ROM_GPIOPinTypePWM(GPIO_PORTF_BASE, GPIO_PIN_2|GPIO_PIN_3);

	// Configure PF2 as M1PWM6, and PF3 as M1PWM7
	ROM_GPIOPinConfigure(GPIO_PF2_M1PWM6|GPIO_PF3_M1PWM7);

	// Unlock the GPIO commit control register (for PF0)
	HWREG(GPIO_PORTF_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY;
	HWREG(GPIO_PORTF_BASE + GPIO_O_CR) |= 0x01;
	HWREG(GPIO_PORTF_BASE + GPIO_O_LOCK) = 0;

	// Set PF4 (SW1) and PF0 (SW2) as input pulled-up
	ROM_GPIODirModeSet(GPIO_PORTF_BASE, GPIO_PIN_4|GPIO_PIN_0, GPIO_DIR_MODE_IN);
	ROM_GPIOPadConfigSet(GPIO_PORTF_BASE, GPIO_PIN_4|GPIO_PIN_0, GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_STD_WPU);

	ui32PWMClock = ROM_SysCtlClockGet() / 64;
	// Load = 625000/20 - 1 = 31249 ticks
	ui32Load = (ui32PWMClock / PWM_FREQUENCY) - 1;

	// Configure M1PWM6 and M1PWM7 as a down-counter (count to zero)
	ROM_PWMGenConfigure(PWM1_BASE, PWM_GEN_3, PWM_GEN_MODE_DOWN);
	ROM_PWMGenPeriodSet(PWM1_BASE, PWM_GEN_3, ui32Load);

	// Set the pulse-width (# of clock ticks)
	ROM_PWMPulseWidthSet(PWM1_BASE, PWM_OUT_6, ui32Load*i32DutyCycle/1000);
	ROM_PWMPulseWidthSet(PWM1_BASE, PWM_OUT_7, ui32Load - ui32Load*i32DutyCycle/1000);
	// Enable the outputs
	ROM_PWMOutputState(PWM1_BASE, PWM_OUT_6_BIT|PWM_OUT_7_BIT, true);
	ROM_PWMGenEnable(PWM1_BASE, PWM_GEN_3);

	while(1)
	{
		if(ROM_GPIOPinRead(GPIO_PORTF_BASE, GPIO_PIN_4) == 0x00)
		{
			i32DutyCycle --;
			if (i32DutyCycle < 0)
			{
				i32DutyCycle = 0;
			}
		}

		if(ROM_GPIOPinRead(GPIO_PORTF_BASE, GPIO_PIN_0) == 0x00)
		{
			i32DutyCycle ++;
			if (i32DutyCycle > 999)
			{
				i32DutyCycle = 999;
			}
		}

		ROM_PWMPulseWidthSet(PWM1_BASE, PWM_OUT_6, ui32Load*i32DutyCycle/1000);
		ROM_PWMPulseWidthSet(PWM1_BASE, PWM_OUT_7, ui32Load - ui32Load*i32DutyCycle/1000);
		ROM_SysCtlDelay(20e3);
	}
}

The first problem is that only the green LED on PF3 works. The blue LED on PF2 never lit up.

Also, when I use "non-ROM" functions, such as changing ROM_SysCtlClockGet() to SysCtlClockGet(), there will be a compilation failure.

**** Build of configuration Debug for project PWM_test ****

"c:\\ti\\ccsv6\\utils\\bin\\gmake" -k all 
'Building file: ../main.c'
'Invoking: ARM Compiler'
"c:/ti/ccsv6/tools/compiler/arm_5.1.6/bin/armcl" -mv7M4 --code_state=16 --float_support=FPv4SPD16 --abi=eabi -me --include_path="c:/ti/ccsv6/tools/compiler/arm_5.1.6/include" --include_path="C:/ti/TivaWare_C_Series-2.1.0.12573" -g --define=PART_TM4C123GH6PM --define=TARGET_IS_BLIZZARD_RB1 --display_error_number --diag_warning=225 --diag_wrap=off --preproc_with_compile --preproc_dependency="main.pp"  "../main.c"
'Finished building: ../main.c'
' '
'Building target: PWM_test.out'
'Invoking: ARM Linker'
"c:/ti/ccsv6/tools/compiler/arm_5.1.6/bin/armcl" -mv7M4 --code_state=16 --float_support=FPv4SPD16 --abi=eabi -me -g --define=PART_TM4C123GH6PM --define=TARGET_IS_BLIZZARD_RB1 --display_error_number --diag_warning=225 --diag_wrap=off -z -m"PWM_test.map" --heap_size=0 --stack_size=512 -i"c:/ti/ccsv6/tools/compiler/arm_5.1.6/lib" -i"c:/ti/ccsv6/tools/compiler/arm_5.1.6/include" --reread_libs --warn_sections --display_error_number --diag_wrap=off --xml_link_info="PWM_test_linkInfo.xml" --rom_model -o "PWM_test.out"  "./tm4c123gh6pm_startup_ccs.obj" "./main.obj" "../tm4c123gh6pm.cmd" -l"libc.a" 
<Linking>

 undefined      first referenced
  symbol            in file     
 ---------      ----------------
 SysCtlClockGet ./main.obj      

error #10234-D: unresolved symbols remain
error #10010: errors encountered during linking; "PWM_test.out" not built

>> Compilation failure
gmake: *** [PWM_test.out] Error 1
gmake: Target `all' not remade because of errors.

**** Build Finished ****

The same issue also occurs while using the very same code provided by the Workshop.

Can anyone help me?