TMS570LS1224: Changing the duty cycle of the NHET1 while configuring as PWM not working

I am configuring the NHET1 as PWM4 . By default the duty cycle =50.

I want to change the duty cycle to 80. So I wrote a code ,like this,

hetInit();      

uint32_t pwm=pwm4;
uint32_t pwmDuty=80;
hetRAMBASE_t * hetRAM=hetREG1;
pwmStop(hetRAM, pwm);
pwmSetDuty(hetRAM,pwm,pwmDuty);
pwmStart(hetRAM, pwm);

I can see only 50 duty cycle PWM at the moment, when I do hetInit();   But I can't see the 80 duty PWM. Can any one help me?