[請問] NCU240 如何啟動 PWM 輸出 ?

我寫了簡單的 Test Code 由 sample code(Smpl_Basic01_PWMDAC)改的 , 但 IO pin (PWM0) 卻一直沒有輸出, 什麼地方錯了 ???
Thanks !!!

main()

{

SYS_Init();

CLK_SetModuleClock( PWM01_MODULE, CLK_CLKSEL1_PWM01_S_HIRC, 0);

CLK_EnableModuleClock( PWM01_MODULE );

SYS->GPA_MFP = SYS_GPA_MFP_PA12_PWM0;

PWM_ConfigOutputChannel( PWMA,0,1000000,50 );

PWM_SET_DIVIDER( PWMA, 0, PWM_CLK_DIV_1 );

PWM_SET_PRESCALER( PWMA, 1, 0 );

PWM_SET_CNR(PWMA, 0, 120);

PWM_SET_CMR(PWMA, 0, 60);

        PWM_Start(PWMA, 0x01);

PWM_EnableOutput(PWMA, 0x01);

GPIO_SetMode(PB, 4, GPIO_PMD_OUTPUT); //LED1

while(1)

        {

PB4 ^= 1;

         PWM_SET_CMR(PWMA, 0, 60);

};

}