TMS320F28379D: External interrupt isn't working during interrupt.

Tool/software:

dear Team, 

I want to set external interrupt during epwm interrupt for protection. 

during ePWM interrupt, I set PIEIFR to be active XINT. 

but it didn't work.

please help it work and where should I check? 

the code is as follow,

initial set 

GPIO_setInterruptType(GPIO_INT_XINT1, GPIO_INT_TYPE_RISING_EDGE);
GPIO_setInterruptPin(11, GPIO_INT_XINT1);
GPIO_enableInterrupt(GPIO_INT_XINT1);
Interrupt_enableInCPU(INTERRUPT_CPU_INT1);

Interrupt_enable(INT_XINT1);

ePWM ISR: 

// // If Fault, raise Fault interrupt by Software
if(flag_fault)
{
PieCtrlRegs.PIEIFR1.bit.INTx4 = 0x01;
}

best regard.