AVR-Chat

I'm trying to enable External Interrupts 6 and 7, but I can't seem to
get them working. 

Here's my init code:

    DDRD  = 0x00;                // set port D for input
    PORTD = 0xff;                // activate internal pull-up

    cbi(EICRB,ISC61);            // set sense control for any edge
    cbi(EICRB,ISC71);
    sbi(EICRB,ISC60);
    sbi(EICRB,ISC70);
    EIMSK = (1<<INT6) | (1<<INT7); // enable interrupts 6 and 7
    sei();    

My main program is just a tight loop.  The interrupt just toggles
an LED.

SIGNAL(SIG_INTERRUPT6)
{
    LED_OFF(RED);
    if (ledOn == 1)
    {
       LED_OFF(BLUE);
       ledOn = 0;
    }else{
       LED_ON(BLUE);
       ledOn = 1;
    }
}


I don't have any indication that the interrupt is firing though.  I
believe I'm hooked up to the right pins on my board (atmega128 btw).

Anything I'm missing to enable these interrupts?

Thanks, 
Ed