Compiler/TMS320F28069: Code execution is not as it is expected

Part Number: TMS320F28069

Tool/software: TI C/C++ Compiler

Hi everybody 

I just create a simple blink LED to check the hardware as follow:

#include "DSP28x_Project.h"
/**
* main.c
*/
int main(void)
{

InitSysCtrl();
DINT;
InitPieCtrl();

//
// Disable CPU interrupts and clear all CPU interrupt flags:
//
IER = 0x0000;
IFR = 0x0000;
InitPieVectTable();
// Initialize GPIOs for the LEDs and turn them off
//
EALLOW;
GpioCtrlRegs.GPBDIR.bit.GPIO34 = 1;
GpioCtrlRegs.GPBDIR.bit.GPIO39 = 1;
GpioDataRegs.GPBDAT.bit.GPIO34 = 1;
GpioDataRegs.GPBDAT.bit.GPIO39 = 1;
GpioCtrlRegs.GPBMUX1.bit.GPIO34=0;
EDIS;
while(1){
GpioDataRegs.GPBDAT.bit.GPIO34=1;
GpioDataRegs.GPBDAT.bit.GPIO39=1;
DELAY_US(1000000);

GpioDataRegs.GPBDAT.bit.GPIO34=0;
// DELAY_US(10);
GpioDataRegs.GPBDAT.bit.GPIO39=0;
DELAY_US(1000000);
GpioDataRegs.GPBDAT.bit.GPIO34=1;
// DELAY_US(10);
GpioDataRegs.GPBDAT.bit.GPIO39=1;

}

return 0;
}

the two LEDs on board suppose to blink but, only the LED of GPIO39 is blinking and LED of GPIO34 is solid on. however if I uncomment those DELAY_US(10)s , program works normally

any answer appreciated 

thanks in advanced