PIC24Fj128ga006 spi-slave problem

Hi....

Need Help

My project - set the controller as spi slave (interrupt base) using MPLAB C30
I can receive data from spi but cannot transmit back - SDO cannot work

this is my code:
void init_spi1(void)
{

//SPI1BUF = 0x00; //clear spi buffer
IFS0bits.SPI1IF = 0x00;//clear interrupt flag status
IEC0bits.SPI1IE = 0x00;//disable spi interrupts

SPI1CON1bits.DISSCK = 0x00;//internal serial clock is enable
SPI1CON1bits.DISSDO = 0x00;//sdo pin control by module
SPI1CON1bits.MODE16 = 0x00;//8 bit operation
SPI1CON1bits.SMP = 0x00;//clr if used in slave mode
SPI1CON1bits.CKE = 0x00;//output data change from active clk to idle clk state

SPI1CON1bits.SSEN = 0x00;//ss used for slave mode
SPI1CON1bits.CKP = 0x00;//idle state for clk-low; active high
SPI1CON1bits.MSTEN = 0x00;//slave mode

SPI1STAT = 0x0004;
SPI1STATbits.SPIROV = 0;
SPI1STATbits.SPIEN |= 1;

IFS0bits.SPI1IF = 0x00;//clear interrupt flag status
IEC0bits.SPI1IE = 0x01;//disable spi interrupts

}

//interrupt

void __attribute__((interrupt,no_auto_psv)) _SPI1Interrupt(void)
{

inSPI[inSPIctr++] = SPI1BUF; //store data receive Increment pointer.
SPI1BUF=0x55; //write data to buffer

if((inSPI[0]==0x01)&&(inSPI[1]==0x02)&&(inSPI[2]==0x03)){
PORTD = 0x00; //if data store equale led on
inSPI[0]=0x00;
inSPIctr = 0x00;
}
else if((inSPI[0]==0x04)&&(inSPI[1]==0x05)&&(inSPI[2]==0x06)){
PORTD = 0x01; //if data store equale led off
inSPI[0]=0x00;
inSPIctr = 0x00;
}

_SPI1IF = 0x00;//clear interrupt flag status
}

//my simulation using protesu